ArticlePDF Available

Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: A randomized trial

Authors:

Abstract and Figures

Background: A dietary protein intake higher than the Recommended Dietary Allowance during an energy deficit helps to preserve lean body mass (LBM), particularly when combined with exercise. Objective: The purpose of this study was to conduct a proof-of-principle trial to test whether manipulation of dietary protein intake during a marked energy deficit in addition to intense exercise training would affect changes in body composition. Design: We used a single-blind, randomized, parallel-group prospective trial. During a 4-wk period, we provided hypoenergetic (∼40% reduction compared with requirements) diets providing 33 ± 1 kcal/kg LBM to young men who were randomly assigned (n = 20/group) to consume either a lower-protein (1.2 g · kg(-1) · d(-1)) control diet (CON) or a higher-protein (2.4 g · kg(-1) · d(-1)) diet (PRO). All subjects performed resistance exercise training combined with high-intensity interval training for 6 d/wk. A 4-compartment model assessment of body composition was made pre- and postintervention. Results: As a result of the intervention, LBM increased (P < 0.05) in the PRO group (1.2 ± 1.0 kg) and to a greater extent (P < 0.05) compared with the CON group (0.1 ± 1.0 kg). The PRO group had a greater loss of fat mass than did the CON group (PRO: -4.8 ± 1.6 kg; CON: -3.5 ± 1.4kg; P < 0.05). All measures of exercise performance improved similarly in the PRO and CON groups as a result of the intervention with no effect of protein supplementation. Changes in serum cortisol during the intervention were associated with changes in body fat (r = 0.39, P = 0.01) and LBM (r = -0.34, P = 0.03). Conclusions: Our results showed that, during a marked energy deficit, consumption of a diet containing 2.4 g protein · kg(-1) · d(-1) was more effective than consumption of a diet containing 1.2 g protein · kg(-1) · d(-1) in promoting increases in LBM and losses of fat mass when combined with a high volume of resistance and anaerobic exercise. Changes in serum cortisol were associated with changes in body fat and LBM, but did not explain much variance in either measure. This trial was registered at clinicaltrials.gov as NCT01776359.
Content may be subject to copyright.
Higher compared with lower dietary protein during an energy deficit
combined with intense exercise promotes greater lean mass gain and
fat mass loss: a randomized trial
1,2
Thomas M Longland, Sara Y Oikawa, Cameron J Mitchell, Michaela C Devries, and Stuart M Phillips*
Department of Kinesiology, Exercise Metabolism Research Group, McMaster University, Hamilton, Canada
ABSTRACT
Background: A dietary protein intake higher than the Recommen-
ded Dietary Allowance during an energy deficit helps to preserve
lean body mass (LBM), particularly when combined with exercise.
Objective: The purpose of this study was to conduct a proof-of-
principle trial to test whether manipulation of dietary protein intake
during a marked energy deficit in addition to intense exercise train-
ing would affect changes in body composition.
Design: We used a single-blind, randomized, parallel-group prospec-
tive trial. During a 4-wk period, we provided hypoenergetic (w40%
reduction compared with requirements) diets providing 33 61 kcal/
kg LBM to young men who were randomly assigned (n= 20/group)
to consume either a lower-protein (1.2 g $kg
21
$d
21
)controldiet
(CON) or a higher-protein (2.4 g $kg
21
$d
21
)diet(PRO).All
subjects performed resistance exercise training combined with high-
intensity interval training for 6 d/wk. A 4-compartment model assess-
ment of body composition was made pre- and postintervention.
Results: As a result of the intervention, LBM increased (P,0.05) in
the PRO group (1.2 61.0kg)andtoagreaterextent(P,0.05)
compared with the CON group (0.1 61.0 kg). The PRO group had
a greater loss of fat mass than did the CON group (PRO: 24.8 61.6 kg;
CON: 23.5 61.4kg; P,0.05). All measures of exercise per-
formance improved similarly in the PRO and CON groups as a result
of the intervention with no effect of protein supplementation. Changes
in serum cortisol during the intervention were associated with changes
in body fat (r=0.39,P=0.01)andLBM(r=20.34, P=0.03).
Conclusions: Our results showed that, during a marked energy def-
icit, consumption of a diet containing 2.4 g protein $kg
21
$d
21
was
more effective than consumption of a diet containing 1.2 g protein $
kg
21
$d
21
in promoting increases in LBM and losses of fat mass
when combined with a high volume of resistance and anaerobic
exercise. Changes in serum cortisol were associated with changes
in body fat and LBM, but did not explain much variance in either
measure. This trial was registered at clinicaltrials.gov as
NCT01776359. Am J Clin Nutr 2016;103:738–46.
Keywords: athlete, dietary protein, leucine, skeletal muscle, resistance
exercise, high-intensity interval training
INTRODUCTION
Hypoenergetic diet–induced weight loss results in w20–30%
of mass lost as lean body mass (LBM),
3
with the remaining mass
lost from adipose tissue (1). Retention of LBM during weight
loss may be important in maintaining physical performance while
also preserving skeletal muscle. Strategies that attenuate the loss of
LBM and even allow gains in LBM to occur during an energy deficit
are of interest to athletes and for health in general. Consuming
supplemental protein during resistance training (RT) can result in an
increased accretion of LBM (2). Evidence from Areta et al. (3)
showed that consuming 30 g protein after resistance exercise while in
an energy deficit resulted in a greater stimulation of muscle protein
synthesis (MPS) than did consumption of 15 g protein. Pasiakos et al.
(4) reported that daily protein at twice the Recommended Dietary
Allowance (RDA) for protein attenuated the loss of LBM during an
energy deficit with both aerobic and resistance exercise. Other re-
search suggests that $2 g protein $kg
21
$d
21
mayberequiredto
maintain LBM when an individual is in an energy deficit (5).
RT attenuates the loss of skeletal muscle mass during an energy
deficit presumably by stimulating MPS (3, 4). Combining a higher
protein intake with RT during caloric restriction would act syner-
gistically on the rates of MPS, resulting in a greater ratio of fat to
LBM lost during energy restriction (5, 6), which may be advan-
tageous for physical performance. In addition, high-intensity interval
training (HIT)/sprint interval training (SIT) during a hypoenergetic
period may also aid in promoting LBM retention (7). HIT/SIT also
results in rapid gains in aerobic fitness, as well as endurance ca-
pacity, thus contributing to physical performance outcomes (8, 9).
In subjects who were in energy balance (or mildly positive energy
balance), exercise-induced changes in hormones such as testosterone,
1
Funded by the Natural Science and Engineering Research Council of
Canada (grant no. RGPIN-2015-04613 to SMP and postgraduate scholar-
ship–doctoral to CJM). This is a free access article, distributed under terms
(http://www.nutrition.org/publications/guidelines-and-policies/license/) that per-
mit unrestricted noncommercial use, distribution, and reproduction in any
medium, provided the original work is properly cited.
2
The funder had no role in the study design, analyses, or interpretation of
the results.
*Towhom correspondence should be addressed. E-mail: phillis@mcmaster.ca.
3
Abbreviations used: CON, lower-protein (1.2 g $kg
21
$d
21
) control
diet; HIT, high-intensity interval training; IGF-I, insulin-like growth factor I;
LBM, lean body mass; MPS, muscle protein synthesis; PRO, higher-protein
(2.4 g $kg
21
$d
21
) diet; RDA, recommended dietary allowance; RT, re-
sistance training; SIT, sprint interval training; 1RM, 1-repetition maximum.
Received July 14, 2015. Accepted for publication December 16, 2015.
First published online January 27, 2016; doi: 10.3945/ajcn.115.119339.
738 Am J Clin Nutr 2016;103:738–46. Printed in USA. Ó2016 American Society for Nutrition
by guest on March 3, 2016ajcn.nutrition.orgDownloaded from
growth hormone, cortisol, and/or insulin-like growth factor I (IGF-I)
were not associated with changes in MPS (10, 11), muscle mass (12,
13), or strength (13). Nonetheless, there is still disagreement on
whether changes in systemic hormones mediate exercise-induced
changes (14). The role of hormones and their association with
body composition under hypoenergetic conditions combined
with high-intensity exercise has been less well studied; however,
when under extreme energy deprivation combined with high
energy expenditure, there have been associations observed
between changes in hormones and body composition (15, 16).
Given the synergistic anabolic properties of RT and dietary
protein, and potentially of HIT/SIT, we evaluated whether
a higher-protein (2.4 g $kg
21
$d
21
) diet (PRO) or a lower-
protein (1.2 g $kg
21
$d
21
) control diet (CON) during
a marked energy deficit (40% reduction compared with re-
quirements) would attenuate the loss or promote the gain of
LBM while RT and HIT/SIT were performed. We hypothe-
sized that, during an energy deficit of w40% compared with
estimated energy requirements (33 61kcal$kg
21
LBM $d
21
)
for 28 d, consumption of the PRO compared with the CON would
allow for better maintenance and possibly augmentation of LBM,
while reducing adipose tissue and enhancing physical function.
METHODS
Research participants
The trial was a single-blind, randomized, parallel prospective
trial conducted between January 2013 and February 2014
(NCT01776359) at McMaster University. The trial protocol was
approved by the Hamilton Integrated Research Ethics Board and
complied with the standards as set out in the Canadian Tri-Council
Policy statement on the use of human participants in research
(http://www.pre.ethics.gc.ca/pdf/eng/tcps2/TCPS_2_FINAL_Web.
pdf). Forty overweight [BMI (in kg/m
2
).25] young men (23 62y,
184 68 cm, 97.4 616 kg) (Table 1) were recruited via posters
and newspaper advertisements from the local Hamilton com-
munity and volunteered to participate in the study after being
informed of the procedures and potential risks involved in the
investigation. All participants were recreationally active (i.e.,
played noncompetitive sports or engaged in some form of
physical activity 1–2 times/wk); however, no participants were
regularly performing resistance exercise nor were they regularly
performing structured progressive aerobic or anaerobic training.
Participants were assessed by medical screening questionnaires at
baseline to exclude those with health conditions that might affect their
response to the study protocol or compromise their safety. Partici-
pants gave informed written consent before the commencement of
the study. Once consent was obtained, participants were randomly
assigned (with the use of the random number generation of a code:
http://www.randomization.com/) by the same investigator (SYO) to
either the CON group, which consumed an energy-restricted diet with
a4063% reduction in energy intake compared with estimated
requirements (33 61 kcal $kg
21
LBM $d
21
; 15% protein, 50%
carbohydrates, and 35% fat), with 1.2 g $kg
21
protein $d
21
,orthe
PRO group, which consumed an energy-restricted diet with a 40 6
3% reduction in energy intake compared with estimated requirements
(33 61 kcal $kg
21
LBM $d
21
; 35% protein, 50% carbohydrates,
and 15% fat), with 2.4 g $kg
21
protein $d
21
. Subject flow through
the protocol is shown in Figure 1. Subjects’ preintervention de-
scriptive characteristics are shown in Table 1.
Experimental protocol
Participants reported to the laboratory and underwent famil-
iarization for all exercises to be performed throughout the study
period. On a separate day, participants underwent a progressive
maximal aerobic capacity test (
_
VO
2max
) on a cycle ergometer
with the use of a ramp protocol as described previously (17). On
a subsequent day, isometric maximal voluntary contraction of
the knee extensors was completed with the use of a Biodex
dynamometer as described below. Participants also performed
a Wingate Anaerobic Test to determine peak anaerobic power
(further description provided below). On a separate day, par-
ticipants reported to the laboratory to measure voluntary isotonic
strength as a 1-repetition maximum (1RM) for bench press and
leg press with the use of established standard operating pro-
tocols (8, 18), which were strictly controlled and followed each
time participants were tested by a single investigator (TML).
Participants were provided with a 3-d diet for weight main-
tenance (w15–18% protein, 55–60% carbohydrate, and 20–25%
fat) with energy requirements based on the Harris–Benedict
equation, with the use of an activity factor estimated based
on the subject’s self-reported habitual daily activities. On day 3
of the maintenance diet, participants reported to the laboratory
after a 10-h overnight fast for body composition–related mea-
sures described in detail below. A blood sample was also taken
from an antecubital vein (see below for details).
Diet
Participants were provided with all meals and beverages to
consume throughout the intervention period (with the exception
of water and noncaloric drinks, which were ad libitum). Diets
corresponded to an individually constructed energy-restricted
meal plan. Participants were placed on a 3-d rotating diet with
lunchtime and dinnertime meals provided as prepackaged frozen
meals (Copper County Foods). Both groups received beverages
containing whey protein to be consumed throughout the day, with
one beverage being consumed immediately after training in the
presence of the investigators on exercise days. The composition
of the beverages is given in Table 2. Compliance with the nu-
tritional intervention (i.e., consumption of all the provided study
foods) was assessed by daily contact with participants, food
consumption checklists, and daily weight monitoring, and was
estimated to be 93%. Deviations from the diet were recorded
and adjustments were made to the subjects’ diets to ensure
a consistent energy deficit. Compliance with the exercise
TABLE 1
Participants’ characteristics before the intervention
1
PRO CON
Age, y 23 622362
Body mass, kg 100.1 612.8 96.0 614.6
Height, m 1.84 60.06 1.84 60.08
BMI, kg/m
2
29.7 63.9 29.6 62.7
Fat mass, kg 22.1 67.3 22.8 67.2
Body fat, % 23.6 66.1 24.8 66.3
LBM, kg 73.0 66.8 69.2 68.1
1
Values are means 6SDs. n= 40 (20/group). See Methods for de-
termination of LBM. CON, lower-protein (1.2 g $kg
21
$d
21
) control diet;
LBM, lean body mass; PRO, higher-protein (2.4 g $kg
21
$d
21
) diet.
HIGHER PROTEIN DURING AN ENERGY DEFICIT 739
by guest on March 3, 2016ajcn.nutrition.orgDownloaded from
protocol was .96% and did not differ between groups (P= 0.89).
Dietary macronutrient breakdown and energy intake for both
groups during the protocol can be found in Tab l e 3 .
Each participant received 3 or 4 dairy-based beverages/d
(depending on their body weight) with ingredients dependent
on their group assignment (Table 2). Specific meals containing
higher or lower protein were consumed so that boluses of protein
were spread out throughout the day. Both drinks were flavored
identically, resulting in no perceptible taste differences in the
drinks (based on a blinded taste test) between groups. Drink
protein content was altered by adding Agropur IsoChill 9010
Instantized Whey Protein Isolate. Maltodextrin was added to each
of the drinks to change their energy content, but also to keep the
protein-to-carbohydrate ratios similar between groups. Blinding
of the subjects to their dietary intervention group was accom-
plished through the subjects’ assigned drinks (Table 2), which
accounted for .90% of the macronutrient differences between
the groups. Given that after study completion subjects guessed
their nutritional assignment at rates no better than chance, we
believe the blinding was reasonable.
Exercise training
Participants reported to the laboratory 6 d/wk for exercise
training that consisted of the following: 1) a full-body resistance
exercise circuit, which was completed 2 times/wk with circuits
(no rest between exercises). Circuits included 10 repetitions/set
for 3 sets at 80% of 1RM, with the last set of each exercise to
volitional failure, with 1 min of rest between sets; 2) HIT/SIT,
which took place 2 times/wk. Sessions consisted of one session
of SIT (progressing from four to eight 30-s Wingate bouts) with
a 4-min rest between bouts (protocol described in detail below),
and a second session of modified HIT consisting of 10 bouts of
an all-out sprint for 1 min at 90% of peak power (watts at
_
VO
2max
), with 1-min rest intervals pedaling at 50 W; 3) a weekly
250-kJ time trial on a cycle ergometer during which participants
were instructed to complete the trial as quickly as possible while
self-adjusting the ergometer resistance; and 4) a plyometric
body weight circuit with a 30-s rest between exercises.
To prevent sedentary activity at nonexercise times, all par-
ticipants were provided with a hip-worn pedometer (AccuSTEP
400; ACCUSPLIT) and were instructed to accumulate at least
10,000 steps/d throughout the trial. Step counts were monitored
on a daily basis and averaged 11,915 62492 steps/d throughout
the intervention, with no differences pre- to postintervention or
FIGURE 1 Subject recruitment and flow through the protocol. CON, lower-protein (1.2 g $kg
21
$d
21
) control diet; PRO, higher-protein (2.4 g $kg
21
$d
21
) diet.
TABLE 2
Dietary intake (including protein beverages) during the intervention
1
PRO CON P
Protein, g 245 631 116 619 ,0.001
Protein, g/kg 2.4 60.1 1.2 60.1 ,0.01
Protein, g/kg LBM 3.3 60.1 1.7 60.1 ,0.001
Carbohydrate, g 311 635 286 635 0.21
Carbohydrate, g/kg 3.1 60.3 3.0 60.2 0.68
Fat, g 38 6686613 0.005
Fat, g/kg 0.4 60.1 0.9 60.1 0.012
1
Values are means 6SDs. n= 40 (20/group). Comparison with the use
of unpaired, 2-tailed Student’s ttest. Values were calculated with the use of
preintervention body mass and LBM only. See Methods for determination of
LBM. CON, lower-protein (1.2 g $kg
21
$d
21
) control diet; LBM, lean body
mass; PRO, higher-protein (2.4 g $kg
21
$d
21
) diet.
740 LONGLAND ET AL.
by guest on March 3, 2016ajcn.nutrition.orgDownloaded from
between groups. Subjects who reported .2 consecutive days of
,10,000 steps/d were instructed to complete greater steps in the
ensuing 2–3 d to ensure that their average number of daily steps
was $10,000.
Body composition
Body composition was determined with the use of a 4-
compartment model of body composition as described pre-
viously (19). Total body volume was determined with the use of
air-displacement plethysmography (BodPod; Cosmed), total
body water was determined with the use of bioelectrical im-
pedance (Maltron Bio-Scan MPR 920-II; Maltron International),
and bone mineral content was determined with the use of dual-
energy X-ray absorptiometry (QDR 4500A, software version
12.31; Hologic). Calculations of body fat and LBM were made
with an equation adapted from Lohman and Going (20). These
measures were performed on the same day after a 10-h fast and
were measured at the same time of day before and upon
completion of the 28-d protocol. Subjects wore only light, form-
fitting shorts for all body composition tests. Subjects were
euhydrated (according to urine specific gravity) and abstained
from physical activity for 48 h before their body composition
testing to minimize variability. CVs for repeated measures on
subsequent days were the following: BodPod, 1.2%; bio-
electrical impendance, 1.9%; and dual-energy X-ray absorpti-
ometry, 0.8%.
Strength and muscular performance
Isometric knee extensor torque was measured with the use of
a Biodex dynamometer as described previously (18). Single best
isotonic lift strength (1RM) testing was conducted in the exercise
testing laboratory with the use of free weights and well-defined
standard operating procedures. Participants were familiarized on
a separate day with both the bench press and leg press exercises
a minimum of 4 d before 1RM testing to reduce muscle soreness/
fatigue that may have occurred as a result of the familiarization.
1RM was determined within 4 attempts with rest periods of 3–5 min
between attempts.
Push-up and sit-up tests were conducted while following strict
standard operating procedures. The maximum number of push-
ups performed with correct form consecutively (without rest) was
counted as the subjects’ score (the same evaluator scored all
participants). The sit-up tests were conducted (with the same
evaluator, TML) so that participants performed as many sit-ups
as possible with good form per protocol in 60 s.
Aerobic and anaerobic testing
Participants performed an incremental test to exhaustion on an
electronically braked cycle ergometer (Excalibur Sport V2.0;
Lode) to determine
_
VO
2max
with the use of an online gas col-
lection system (Moxus modular oxygen uptake system; AEI
technologies). On the test day, participants were instructed to
warm up for 10 min on a cycle ergometer at a low resistance
(70 W). Participants then completed the protocol as previously
described (17), with verbal encouragement throughout the test.
The measurement began with the participant cycling at a work-
load of 70 W with wattage increasing at 1 W/s thereafter.
A Wingate Anaerobic Test was performed on an electronically
braked cycle ergometer (Wingate Velotron Racemate), as de-
scribed (21), against a resistance equivalent to 0.075 kg/kg body
mass. Peak and mean power were subsequently determined with
the use of an online data acquisition system. During the 4-min
recovery period between tests, subjects remained on the cycle
ergometer and either rested or were permitted to cycle at a low
cadence (50 rpm) against a light resistance (30 W) to reduce
venous pooling in the lower extremities.
A time trial with the use of methods described previously (21)
was completed on a day separate from all other testing before and
weekly during the intervention, as well as after the intervention
was completed. In brief, subjects were instructed to complete
250-kJ self-paced work laboratory time trials on an electronically
braked cycle ergometer (Excalibur Sport V2.0; Lode) as quickly
as possible with no temporal, verbal, or physiologic feedback.
The only feedback provided during the time trials was work
completed, which was presented as “distance covered” (e.g., 250 kJ
was equated to 10 km such that visual feedback at any point
during the time trial was presented in units of distance rather
than work completed).
Blood sampling, hormonal measurements, and urinary
measures
Blood was sampled by venipuncture from subjects after a 10-h
overnight fast before the intervention and 48 h after the last
training session at the end of the intervention. Blood was col-
lected in evacuated tubes and allowed to clot for 15 min at room
temperature before being centrifuged at 48C for 15 min at
1500 3g. Serum was subsequently removed and stored at
2808C before analysis. Urine collections (24-h) were initiated
after the first morning urinary void and collected into sterile
urine jugs. Urine was stored at 48C during collection and was
returned to the laboratory the morning after the 24 collection
period ended. Urine volume was measured and aliquots of urine
(w1.5 mL each) were placed into tubes for storage at 2208C
before analysis.
All analyses were carried out at the core clinical chemistry
facilities at McMaster University Medical Centre with the use of
the procedures used and described by our group previously (11,
13). In brief, serum samples were analyzed for cortisol, sex
hormone binding globulin, total and free testosterone, growth
hormone, ghrelin, and total and free IGF-I with the use of solid-
phase, 2-site chemiluminescence immunometric assays (Immu-
lite; Intermedico) ora 2-site immunoradiometric assay (Diagnostic
Systems Laboratories). All intra- and interassay CVs for these
hormones were ,8%, with the exception of free testosterone,
which was ,11%. Blood urea nitrogen was measured with the
TABLE 3
Composition of study drinks
1
PRO CON P
Protein, g 49 661564,0.001
Carbohydrate, g 48 674166 0.13
Fat, g 2 601263,0.01
Energy, kcal 372 635 330 656 0.02
1
Values are means 6SDs. n= 40 (20/group). Comparison with the use of
unpaired, 2-tailed Student’s ttest. CON, lower-protein (1.2 g $kg
21
$d
21
)
control diet; PRO, higher-protein (2.4 g $kg
21
$d
21
)diet.
HIGHER PROTEIN DURING AN ENERGY DEFICIT 741
by guest on March 3, 2016ajcn.nutrition.orgDownloaded from
use of an automated assay system (Beckman Synchron LX20).
Serum and urinary creatinine were measured with the use of an
automated assay system (HumaStar 600), which is traceable to
isotope dilution mass spectrometry. Intra- and interassay
CVs for these metabolites were all ,5%. Using the serum
and urinary creatinine concentrations, we calculated creati-
nine clearance. Using serum creatinine, we calculated the es-
timated glomerular filtration rate with the use of the Chronic
Kidney Disease Epidemiology Collaboration equation (22), with
appropriate race- and age-specific adjustments.
Statistical analysis
Sample sizes were determined a priori powered on the
primary outcome of lean mass loss (by dual-energy X-ray
absorptiometry) to detect a differential lean mass loss of 1 kg,
with a= 0.05 and power at 90%, to require 16 subjects/group
at a higher (2.4 g $kg
21
$d
21
) and lower (1.2 g $kg
21
$d
21
)
protein intake in an equivalent energy deficit as used in the
current protocol (based on pilot data collected in our laboratory).
Data were assessed for normality with the use of a Kolmogorov–
Smirnov test, and any non-normal data (glomerular filtration
rate, testosterone, free testosterone, growth hormone, and cor-
tisol) were corrected with the use of logarithmic transformation
to ensure that kurtosis and skewedness were within normal
bounds. Nonpaired pre- and postintervention data for groups
were compared with the use of an unpaired Student’s ttest. All
data were analyzed with the use of a 2-factor repeated measures
ANCOVA with protein intake (between) and time (within) as the
main variables. Covariates included age, height, weight, baseline
body composition (when assessing body composition), and
baseline performance measures (when assessing changes in
performance). Significant interaction effects were analyzed with
the use of Tukey’s post hoc test to determine the location of
pairwise differences within (time) and/or between (diet). Pear-
son’s product-moment correlation coefficients were used to
evaluate the relations between variables. Statistical significance
was set at a#0.05. Analyses were performed with the use of
SPSS (version 20.0.0). Data are presented as means 6SDs.
RESULTS
There was substantial weight loss in both groups from pre- to
postintervention, but there were no differences in body weight
loss between groups (P.0.8) (Figure 2). During the in-
tervention, LBM remained unchanged in the CON group (0.1 6
1.0 kg; P,0.45); however, LBM increased in the PRO group
(1.2 61.0 kg) compared with preintervention, and this increase
was greater (P,0.05) than in the CON group. Both PRO and
CON groups showed a decrease in fat mass after the intervention
(P,0.001); however, fat mass losses were greater (P,0.05) in
the PRO group (24.8 61.6 kg) than in the CON group (23.5 6
1.4 kg) (Figure 2). Pre- and postintervention body composition
means are shown in Table 4.
With the exception of isometric knee extension torque,
strength increased in all exercises, as did measures of aerobic and
anaerobic capacity and performance on sit-up and push-up tests
(Table 4). There were no differences between groups for any
performance-based variable.
We observed a significant time-by-condition interaction for
blood urea nitrogen, which increased in the PRO group (P,
0.05) and remained unchanged in the CON group (Table 5).
Creatinine clearance remained unchanged as a result of the
protocol in both groups (Table 4); however, the estimated glo-
merular filtration rate increased in the PRO group from pre- to
postintervention, but remained unchanged in the CON group
(Table 4).
Hormone and metabolite concentrations measured pre- and
postintervention are shown in Table 5. We observed main effects
for time for all hormones and no between-group differences. We
performed correlational analyses between pre- and post-
intervention hormonal concentrations and body composition
pre- and postintervention, or changes in body composition, and
saw no significant relations (all P.0.35) between any variables
(data not shown). The correlations between the absolute changes
in hormones, thought to be pertinent in determining body
composition change (15, 16), are shown in Figures 3 and 4,as
are the measured changes in fat mass (Figure 3) and LBM
(Figure 4). As Figures 3 and 4 show, there was no correlation
between changes in the concentration of any hormone other than
cortisol, and changes in body fat or LBM. Pooling the data from
the PRO and CON groups, we noted that the intervention-induced
change in resting overnight-fasting cortisol was significantly
correlated with the change in body fat (r=0.39,P= 0.01) (Figure
4) and LBM (r=20.34, P= 0.03) (Figure 5). Despite being
statistically significant, the pooled changes in cortisol could ex-
plain only 16% and 11% of the variance in changes in fat mass
and LBM, respectively.
DISCUSSION
We conducted a controlled feeding study in young overweight
men with a protein intake that was close to habitual (CON), but
still greater than the protein RDA, and at an amount 3 times the
protein RDA (PRO). We included forms of exercise that would
promote rapid gains in fitness and strength, as well as promotion
of lean mass retention; however, we also implemented post-
exercise provision of a predominantly whey protein supplement
to augment lean mass preservation in the face of a marked (40%)
energy deficit. The novel finding of the present study was that
a higher protein–containing (2.4 g $kg
21
$d
21
) diet consumed
during a period of marked energy deficit (w40% reduction in
estimated energy requirement) during HIT resulted in an
FIGURE 2 Four-compartment model-derived changes in BM, LBM,
and FM during the intervention in both PRO and CON groups; data were
analyzed with the use of an unpaired ttest. Values are means 6SDs; n=40
(20/group). *Significantly different from CON (P,0.05). BM, body mass;
CON, lower-protein (1.2 g $kg
21
$d
21
) control diet; FM, fat mass; LBM,
lean body mass; PRO, higher-protein (2.4 g $kg
21
$d
21
) diet.
742 LONGLAND ET AL.
by guest on March 3, 2016ajcn.nutrition.orgDownloaded from
increase in LBM. In addition, we observed a greater loss (w1.3 kg)
of fat mass in the PRO group than in the CON group. Although
consumption of higher protein resulted in LBM accretion
(w1.1 kg), it should be noted that LBM was unchanged during
a period of high-intensity exercise training and substantial energy
deficit even when the amount of protein consumed (1.2 g $kg
21
$d
21
)
was lower. Despite differences in body composition changes
between groups, and in contrast to our hypotheses, there were
no differential responses in strength, performance, aerobic
fitness, or anaerobic power between groups in response to the
intervention.
Several studies have examined the impact of a higher protein
intake and resistance exercise on retention of LBM during energy
deficit (4–6, 23, 24). Pasiakos et al. (4) reduced the energy intake
of young men by 30% from estimated requirements while they
performed daily low-to-moderate–intensity (40–60%
_
VO
2max
)
treadmill and cycling as well as thrice weekly lower-intensity
resistive-type exercise (3 sets of 15 repetitions). Contrary to our
findings, these authors (4) reported that a higher protein diet
(2.4 g $kg
21
$d
21
) still resulted in a loss of 1.2 60.3 kg LBM
as a result of the 21-d intervention. These authors (4) included
groups that consumed protein at 3 levels—0.8, 1.6, and 2.4 g $
kg
21
$d
21
—and reported a substantial retention of LBM for
the 1.6 g $kg
21
$d
21
group, but not with consumption of 2.4 g $
kg
21
$d
21
of protein. This finding is somewhat congruent with our
observation that the 1.2 g $kg
21
$d
21
of dietary protein in the
current study resulted in retention of LBM. We propose that the
disparate findings of the previous study (4) and our findings may
be due to the timing of our supplementation and the exercise
intensity, which could be important in increasing or maintaining
LBM while in a severe energy deficit (3). Previously, Mettler
et al. (5) showed that during a 2-wk study, neither 1.0 nor 2.3 g $
kg
21
$d
21
protein were sufficient to prevent LBM loss during
a period of energy restriction similar to that which we used. We
are unable to ascertain exactly why our data are different from
those of the previous study (5); however, some possibilities in-
clude the fact that our intervention was longer (4 compared with
2 wk), our subjects received controlled diets, our subjects un-
derwent individually supervised exercise sessions, and we used
a 4-compartment model of body composition (considered to be
of greater validity than simply dual-energy X-ray absorptiom-
etry data) and had timed (postexercise) ingestion of protein
drinks. It is also worth noting that our training program involved
intense high-volume resistance exercise and HIT/SIT, which has
not, to our knowledge, been studied in such a severe energy
deficit previously.
In the current study, the loss of fat mass was the sole con-
tributor to the participants’ weight loss. Data from Trapp et al.
(25) suggest that lipolysis increases over 20 min of HIT training
gradually with each session. This research suggests that the
high-intensity exercise our current participants were subjected to
likely enhanced their capacity for fat oxidation and may have
induced an increase in muscle mitochondrial enzyme activity
(25). Evidence from the current trial suggests that high-quality
weight loss (i.e., weight loss with a high fat:LBM ratio), is at-
tainable during marked energy restriction with a higher intake of
TABLE 4
Participants’ anthropometric, performance, and renal function variables before and after the intervention
1
PRO CON
Pre Post Pre Post
Body mass, kg 100.1 612.8 94.2 613.7*
y
96 614.6 92.5 614.0*
Body fat, kg 23.6 65.6 18.8 66.2*
y
24.8 66.1 21.1 66.1*
Lean mass, kg 73.1 66.8 74.3 66.7*
y
69.2 66.1 69.2 66.1*
Leg press 1RM,
2
kg 171 630 340 677* 162 630 318 662*
Bench press 1RM,
2
kg 107 629 146 655* 99 614 126 636*
Isometric knee extension MVC, Nm 329 659 336 667 316 647 328 646
Push-ups,
3
count 29 612 39 610* 24 610 31 612*
Sit-ups,
3
count 36 694768* 33 612 44 613*
Peak power,
4
W 1148 6130 1277 6133* 1095 6249 1237 6205*
Mean power,
4
W 768 676 805 676* 707 683 743 698*
Total work,
4
kJ 23.0 62.3 24.1 62.3* 20.9 62.7 22.2 63.0*
_
VO
2max
,mL$kg
21
$min
21
41.1 65.6 46.4 68.4* 40.5 64.9 47.4 66.9*
Time trial performance,
5
min 19.15 63.90 15.62 62.88* 21.21 63.71 17.15 62.37
Creatinine clearance, mL/min 116 68 121 614 112 611 115 616
eGFR, mL $min
21
$1.73 m
22
109.8 68.8 114.3 611.1* 114.3 610.9 116.8 611.2
1
Values are means 6SDs. n= 40 (20/group). All data were analyzed with the use of a 2-factor repeated measures
ANCOVA with protein intake (between) and time (within) as the main variables. Covariates included age, height, weight,
baseline body composition (when assessing changes in body composition), and baseline performance measures (when
assessing changes in performance). No significant differences between groups at baseline. *Significantly different from Pre
(P,0.05);
y
significantly different from CON (P,0.05). See Methods for details of all tests. CON, lower-protein (1.2 g $
kg
21
$d
21
) control diet; eGFR, estimated glomerular filtration rate; MVC, maximal voluntary contraction force; Nm,
Newton-meters; Post, postintervention; Pre, preintervention; PRO, higher-protein (2.4 g $kg
21
$d
21
)diet;1RM,
1-repetition maximum.
2
Maximal isotonic strength measured as single best weight lifted or 1RM.
3
Maximum number of push-ups or sit-ups completed with form.
4
Relevant performance variables from the Wingate test.
5
Time trial to complete 250 kJ of work.
HIGHER PROTEIN DURING AN ENERGY DEFICIT 743
by guest on March 3, 2016ajcn.nutrition.orgDownloaded from
dietary protein in overweight young men. We have previously
reported a similar pattern of body composition change during
a longer-duration intervention in overweight/obese pre-
menopausal women (6). We propose that the lean mass–enhancing
effect is one mediated by protein, as meta-analyses have shown
(26, 27). In these same analyses, the authors noted an effect of
protein in mediating a greater loss of fat mass (26, 27); how-
ever, in these studies, as in our study, the impact of changing
other macronutrients needs to be recognized. We chose to
lower fat intake in the PRO group and match carbohydrate
intake between groups, knowing the impact that carbohydrate
has on exercise performance (28). Thus, we acknowledge that
a strict ascription of the phenotypic changes we observed to
differential protein content of the diet per se is in light of the
differing fat intake between the PRO and CON groups.
Nonetheless, we are unaware of data that would suggest that
a greater or lesser fat intake, at least of the magnitude seen here,
would promote differential lean mass retention and/or differ-
ential fat loss when the energy deficit is identical.
Our data suggest that during a substantial energy deficit, higher
protein consumption (2.4 g $kg
21
$d
21
)resultedinanin-
creased stimulation of MPS and/or a suppression of proteolysis
to a greater extent than consumption of 1.2 g $kg
21
$d
21
,as
evidenced by gains in LBM in the PRO group. Current evidence
suggests that the energy deficit likely reduces basal MPS (29)
and may also have reduced the sensitivity of MPS to feeding
(30, 31). Nonetheless, recent data have shown that lower rates of
MPS can also be restored by a higher dietary protein intake (3),
particularly so with whey protein (30), which was the supple-
mental protein source used herein. Data from our laboratory
have shown that w0.25 g protein $kg
21
per meal (or 0.4 g
protein $kg
21
per meal as a safe intake amount) maximally
stimulates MPS in young men when participants are in energy
balance (32); however, it has not yet been established what
protein dose would maximally stimulate MPS while in a period
of energy deficit. The data from Areta et al. (3) do show that,
while in an energy deficit, larger protein doses .0.25 g $kg
21
per meal continued to stimulate MPS after resistance exer-
cise. In the current study, participants in the PRO group
regularly consumed w49 g protein/meal (w0.48 g $kg
21
per
meal), resulting in repeated periods of maximally stimulated
MPS compared with the CON group, which consumed w22 g
protein per meal (w0.23 g $kg
21
per meal). Importantly, the
FIGURE 3 Linear relations between changes in resting fasting systemic serum hormone concentration and changes in fat mass. Changes in T
free
and fat
mass (A); changes in GH and fat mass (B); changes in cortisol and fat mass (C); and changes in IGF-I
free
and fat mass (D). Values are individual per-subject
data points; n= 40 (20/group). Solid lines indicate linear regression line of best fit 695% CIs (dashed lines). Pvalues are from calculated Pearson correlation
coefficients, and the proportion of variance explained is shown as r
2
values. GH, growth hormone; IGF-I
free
, free insulin-like growth factor I; T
free
, free
testosterone.
TABLE 5
Fasting systemic blood hormone and metabolite concentrations before and
after the intervention
1
PRO CON
Pre Post Pre Post
T
total
, ng/dL 507 623 126 619* 586 633 113 618*
SHBG, nM 78 613 108 616* 88 616 119 614*
T
free
, pg/mL 15.1 62.8 6.7 64.7* 17.8 63.1 6.8 65.1*
GH, ng/mL 8.2 62.5 10.9 63.7* 9.4 62.8 12.8 63.6*
IGF-I
total
, ng/mL 328 619 238 628* 314 618 276 626*
IGF-I
free
, ng/mL 3.8 60.6 1.3 60.5* 3.3 60.6 1.3 60.6*
Cortisol, nM 275 621 452 651* 303 619 509 647*
Ghrelin, pg/mL 495 639 788 692* 515 646 833 6101*
Insulin, mIU/mL 12.2 62.6 6.7 63.2* 11.3 62.9 5.9 63.3*
BUN, mmol/L 5.6 61.1 9.9 62.2*
+
5.9 61.0 6.1 61.1
1
Values are means 6SDs. n= 40 (20/group). All data were analyzed
with the use of a 2-factor repeated measures ANCOVA with protein intake
(between) and time (within) as the main variables. Covariates included age,
height, weight, and baseline hormonal concentration. *Significantly different
from Pre (P,0.01);
+
significantly different from CON (P,0.001). BUN,
blood urea nitrogen; CON, lower-protein (1.2 g $kg
21
$d
21
) control diet;
GH, growth hormone; IGF-I
free
, free insulin-like growth factor I; IGF-I
total
,
total insulin-like growth factor I; Post, postintervention; Pre, preintervention;
PRO, higher-protein (2.4 g $kg
21
$d
21
) diet; SHBG, sex hormone–binding
globulin; T
free
, free testosterone; T
total
, total testosterone.
744 LONGLAND ET AL.
by guest on March 3, 2016ajcn.nutrition.orgDownloaded from
CON group also consumed enough protein combined with an-
abolic exercise throughout the intervention to retain muscle
mass. We hypothesize, given our data, that protein dose per
meal, protein quality, and timing of consumption relative to
exercise would become more important in determining changes
in LBM when in a caloric deficit because of decreases in basal
rates of MPS and a reduced sensitivity of MPS to protein
feeding (29–31).
Resting, overnight-fasting hormonal concentrations were
made before and after the intervention (Table 5). We did not
observe any interaction effects between conditions, but did ob-
serve main effects over time for all hormones (Table 5). In
addition, we did not observe any independent correlations with
hormones or any body composition or performance variables
(data not shown). Our hormonal data align roughly with previous
work in military personnel undergoing high levels of daily ac-
tivity in an extreme energy deficit (15, 16). In the study described
in these publications (15, 16), the degree of energy deficit was
greater and protein intake was much lower than in the present
study. These authors did not observe that increasing protein from
0.5 to 0.9 g $kg
21
$d
21
aided in the retention of LBM (15, 16);
however, we speculate that these levels of protein intake would
not be adequate to spare LBM in such a severe energy deficit
(33), so the lack of a protein-sparing effect (15, 16) is not
surprising. We observed that 1.2 g $kg
21
$d
21
ablated the
usual decline in LBM seen during an energy deficit (1), and that
2.4 g $kg
21
$d
21
allowed for an increase in LBM to occur. It
is more than likely, however, that our results were due as much,
if not more, to the addition of resistance exercise, which acts
synergistically to stimulate MPS even in an energy deficit (3).
The percentage change in free IGF-I was, in the previous work
(16), shown to be correlated with the percentage change in fat
mass; however, our results did not show a similar correlation
(Figure 4). The only hormonal change we observed that was
related to changes in body composition was the change in
cortisol (Figures 4 and 5). In general, cortisol opposes fat loss
and promotes loss of LBM during energy restriction (34),
which is what we observed.
A potential limitation of the present trial is the free-living
nature of the protocol. We did provide all food and beverages to
the subjects and asked them to consume everything we provided
and report any deviation from their prescribed diet. As an ob-
jective measure of compliance with the PRO diet, we measured
serum urea and noted that it increased during the intervention and
remained unchanged in the CON group. We had good compliance
with exercise intervention and propose that subjects exerted high
degrees of effort when requested. Because of the nature of the
trial, it was impractical to maintain a double-blinded scheme, and
yet we do not think this influenced the outcomes, because all
analyses were done in a blinded manner and data were only
unblinded after all analyses were complete. We opted in this trial
to keep carbohydrate intake constant between the groups, given
the crucial role that fuel plays in performance (28); thus, fat
content (Table 2), in addition to protein, was different between
the groups. Hence, given that there were differences in fat
content, it cannot be stated conclusively that it was protein that
was responsible for the effects we report here. However, in
conducting a thorough search for manipulations in dietary fat
content to the degree to which we changed it in our protocol, we
could find nothing that would suggest that differing fat content
would affect changes in LBM or fat mass. Thus, we propose that
the effects were predominantly a protein-mediated effect.
In summary, the present study provides evidence that, in young
men, consuming a higher protein diet (2.4 g $kg
21
$d
21
) during
energy deficit (w40% reduction in energy intake compared with
requirements) while performing intense resistance exercise training
and HIT can augment LBM over a 28-d period. Furthermore, these
high-intensity exercises performed during a period of energy
deficit have the ability to preserve LBM despite a lower protein
intake (1.2 g $kg
21
$d
21
). In conclusion, the current study
provides direct evidence that a higher protein diet during substantial
energy deficit and HIT not only preserves, but increases, LBM and
FIGURE 4 Linear relations between changes in resting fasting systemic serum hormone concentration and changes in LBM. Changes in T
free
and lean mass (A);
changes in GH and lean mass (B); changes in cortisol and lean mass (C); and changes in IGF-I
free
and lean mass (D). Values are individual per-subject data points; n=40
(20/group). Solid lines indicate linear regression line of best fit 695% CIs (dashed lines). Pvalues are from calculated Pearson correlation coefficients, and the proportion
of variance explained is shown as r
2
values. GH, growth hormone; IGF-I
free
, free insulin-like growth factor I; LBM, lean body mass; T
free
, free testosterone.
HIGHER PROTEIN DURING AN ENERGY DEFICIT 745
by guest on March 3, 2016ajcn.nutrition.orgDownloaded from
HIT during the energy deficit, irrespective of protein intake, and
increases strength and performance in young men.
The authors’ responsibilities were as follows—TML and SMP: designed
the research (project conception, development of overall research plan, and
study oversight), and had primary responsibility for the final content; TML,
SYO, and SMP: analyzed data or performed statistical analysis; and all
authors: conducted the research (hands-on conduct of the experiments and
data collection), wrote and/or edited the manuscript, and read and approved
the final manuscript. SMP has received research funding, travel allowances,
and honoraria from the US National Dairy Council and Dairy Farmers of
Canada. None of the other authors reported a conflict of interest related to
the study.
REFERENCES
1. Weinheimer EM, Sands LP, Campbell WW. A systematic review of the
separate and combined effects of energy restriction and exercise on fat-
free mass in middle-aged and older adults: implications for sarcopenic
obesity. Nutr Rev 2010;68:375–88.
2. Cermak NM, Res PT, de Groot LC, Saris WH, van Loon LJ. Protein
supplementation augments the adaptive response of skeletal muscle to
resistance-type exercise training: a meta-analysis. Am J Clin Nutr
2012;96:1454–64.
3. Areta JL, Burke LM, Camera DM, West DW, Crawshay S, Moore DR,
Stellingwerff T, Phillips SM, Hawley JA, Coffey VG. Reduced resting
skeletal muscle protein synthesis is rescued by resistance exercise and
protein ingestion following short-term energy deficit. Am J Physiol
Endocrinol Metab 2014;306:E989–97.
4. Pasiakos SM, Cao JJ, Margolis LM, Sauter ER, Whigham LD,
McClung JP, Rood JC, Carbone JW, Combs GF Jr., Young AJ. Effects
of high-protein diets on fat-free mass and muscle protein synthesis
following weight loss: a randomized controlled trial. FASEB J 2013;
27:3837–47.
5. Mettler S, Mitchell N, Tipton KD. Increased protein intake reduces
lean body mass loss during weight loss in athletes. Med Sci Sports
Exerc 2010;42:326–37.
6. Josse AR, Atkinson SA, Tarnopolsky MA, Phillips SM. Increased con-
sumption of dairy foods and protein during diet- and exercise-induced
weight loss promotes fat mass loss and lean mass gain in overweight and
obese premenopausal women. J Nutr 2011;141:1626–34.
7. Heydari M, Freund J, Boutcher SH. The effect of high-intensity in-
termittent exercise on body composition of overweight young males.
J Obes 2012;2012:480467.
8. Burgomaster KA, Howarth KR, Phillips SM, Rakobowchuk M, Mac-
Donald MJ, McGee SL, Gibala MJ. Similar metabolic adaptations
during exercise after low volume sprint interval and traditional en-
durance training in humans. J Physiol 2008;586:151–60.
9. Gillen JB, Percival ME, Skelly LE, Martin BJ, Tan RB, Tarnopolsky
MA, Gibala MJ. Three minutes of all-out intermittent exercise per
week increases skeletal muscle oxidative capacity and improves car-
diometabolic health. PLoS One 2014;9:e111489.
10. West DW, Kujbida GW, Moore DR, Atherton P, Burd NA, Padzik JP,
De LM, Tang JE, Parise G, Rennie MJ, et al. Resistance exercise-induced
increases in putative anabolic hormones do not enhance muscle protein
synthesis or intracellular signalling in young men. J Physiol 2009;587:
5239–47.
11. West DW, Burd NA, Churchward-Venne TA, Camera DM, Mitchell CJ,
Baker SK, Hawley JA, Coffey VG, Phillips SM. Sex-based compari-
sons of myofibrillar protein synthesis after resistance exercise in the fed
state. J Appl Physiol 2012;112:1805–13.
12. West DW, Burd NA, Tang JE, Moore DR, Staples AW, Holwerda AM,
Baker SK, Phillips SM. Elevations in ostensibly anabolic hormones
with resistance exercise enhance neither training-induced muscle hyper-
trophy nor strength of the elbow flexors. J Appl Physiol 2010;108:60–7.
13. West DW, Phillips SM. Associations of exercise-induced hormone
profiles and gains in strength and hypertrophy in a large cohort after
weight training. Eur J Appl Physiol 2012;112:2693–702.
14. Schroeder ET, Villanueva M, West DD, Philips SM. Are acute post-
resistance exercise increases in testosterone, growth hormone, and IGF-
1 necessary to stimulate skeletal muscle anabolism and hypertrophy?
Med Sci Sports Exerc 2013;45:2044–51.
15. Alemany JA, Nindl BC, Kellogg MD, Tharion WJ, Young AJ, Montain
SJ. Effects of dietary protein content on IGF-I, testosterone, and body
composition during 8 days of severe energy deficit and arduous
physical activity. J Appl Physiol 2008;105:58–64.
16. Nindl BC, Alemany JA, Kellogg MD, Rood J, Allison SA, Young AJ,
Montain SJ. Utility of circulating IGF-I as a biomarker for assessing
body composition changes in men during periods of high physical
activity superimposed upon energy and sleep restriction. J Appl Physiol
2007;103:340–6.
17. Di Donato DM, West DW, Churchward-Venne TA, Breen L, Baker SK,
Phillips SM. Influence of aerobic exercise intensity on myofibrillar and
mitochondrial protein synthesis in young men during early and late post-
exercise recovery. Am J Physiol Endocrinol Metab 2014;306:E1025–32.
18. Mitchell CJ, Churchward-Venne TA, West DD, Burd NA, Breen L, Baker
SK, Phillips SM. Resistance exercise load does not determine training-
mediated hypertrophic gains in young men. J Appl Physiol 2012;113:71–7.
19. Wilson J P, Strauss B J, Fan B, Duewer FW, Shepherd JA. Improved
4-compartment body-composition model for a clinically accessible
measure of total body protein. Am J Clin Nutr 2013;97:497–504.
20. Lohman TG, Going SB. Multicomponent models in body composition
research: opportunities and pitfalls. Basic Life Sci 1993;60:53–8.
21. Bennett JA, Lyons KS, Winters-Stone K, Nail LM, Scherer J. Moti-
vational interviewing to increase physical activity in long-term cancer
survivors: a randomized controlled trial. Nurs Res 2007;56:18–27.
22. Levey AS, Stevens LA, Schmid CH, Zhang YL, Castro AF III, Feldman
HI, Kusek JW, Eggers P, Van LF, Greene T, et al. A new equation to
estimate glomerular filtration rate. Ann Intern Med 2009;150:604–12.
23. Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J. Effect
of two different weight-loss rates on body composition and strength
and power-related performance in elite athletes. Int J Sport Nutr Exerc
Metab 2011;21:97–104.
24. Pikosky MA, Smith TJ, Grediagin A, Castaneda-Sceppa C, Byerley L,
Glickman EL, Young AJ. Increased protein maintains nitrogen balance during
exercise-induced energy deficit. Med Sci Sports Exerc 2008;40:505–12.
25. Trapp EG, Chisholm DJ, Freund J, Boutcher SH. The effects of high-
intensity intermittent exercise training on fat loss and fasting insulin
levels of young women. Int J Obes (Lond) 2008;32:684–91.
26. Krieger JW, Sitren HS, Daniels MJ, Langkamp-Henken B. Effects of
variation in protein and carbohydrate intake on body mass and com-
position during energy restriction: a meta-regression. Am J Clin Nutr
2006;83:260–74.
27. Wycherley TP, Moran LJ, Clifton PM, Noakes M, Brinkworth GD.
Effects of energy-restricted high-protein, low-fat compared with stan-
dard-protein, low-fat diets: a meta-analysis of randomized controlled
trials. Am J Clin Nutr 2012;96:1281–98.
28. Burke LM, Hawley JA, Wong SH, Jeukendrup AE. Carbohydrates for
training and competition. J Sports Sci 2011;29(Suppl 1):S17–27.
29. Pasiakos SM, Vislocky LM, Carbone JW, Altieri N, Konopelski K,
Freake HC, Anderson JM, Ferrando AA, Wolfe RR, Rodriguez NR.
Acute energy deprivation affects skeletal muscle protein synthesis and
associated intracellular signaling proteins in physically active adults.
J Nutr 2010;140:745–51.
30. Hector AJ, Marcotte GR, Churchward-Venne TA, Murphy CH, Breen
L. von AM, Baker SK, Phillips SM. Whey protein supplementation pre-
serves postprandial myofibrillar protein synthesis during short-term energy
restriction in overweight and obese adults. J Nutr 2015;145:246–52.
31. Murphy CH, Churchward-Venne TA, Mitchell CJ, Kolar NM, Kassis
A, Karagounis LG, Burke LM, Hawley JA, Phillips SM. Hypoenergetic
diet-induced reductions in myofibrillar protein synthesis are restored
with resistance training and balanced daily protein ingestion in older
men. Am J Physiol Endocrinol Metab 2015;308:E734–43.
32. Moore DR, Churchward-Venne TA, Witard O, Breen L, Burd NA,
Tipton KD, Phillips SM. Protein ingestion to stimulate myofibrillar
protein synthesis requires greater relative protein intakes in healthy older
versus younger men. J Gerontol A Biol Sci Med Sci 2015;70:57–62.
33. Churchward-Venne TA, Murphy CH, Longland TM, Phillips SM. Role
of protein and amino acids in promoting lean mass accretion with re-
sistance exercise and attenuating lean mass loss during energy deficit in
humans. Amino Acids 2013;45:231–40.
34. Seimon RV, Hostland N, Silveira SL, Gibson AA, Sainsbury A. Effects
of energy restriction on activity of the hypothalamo-pituitary-adrenal
axis in obese humans and rodents: implications for diet-induced
changes in body composition. Horm Mol Biol Clin Investig 2013;15:
71–80.
746 LONGLAND ET AL.
by guest on March 3, 2016ajcn.nutrition.orgDownloaded from
... In addition, mechanical loading, such as in RT, interacts synergistically with a high-protein diet to further elevate MPS (Phillips et al. 1997;Churchward-Venne et al. 2012). Even during CR, this combination has been shown to preserve lean mass in obese individuals (Rice et al. 1999;Longland et al. 2016) and elite-level athletes (Garthe et al. 2011). However, these findings cannot be extrapolated to resistance-trained individuals due to divergent intracellular (Moberg et al. 2020) and MPS responses (Tang et al. 2008;Damas et al. 2015), as well as blood metabolome differences (Schranner et al. 2021) between populations. ...
... These findings suggest that increasing RT volume could possibly elicit lean tissue accretion in recreationally trained athletes under conditions of CR. The results are in accordance with other studies (Garthe et al. 2011;Longland et al. 2016;Barakat et al. 2020), suggestive of a mediating effect of RT experience on lean mass sparing during CR. Consequently, findings using RT beginners or novice athletes cannot be extrapolated to populations who are chronically adapted to RT. Beginners or novice athletes are hypersensitized to RT-induced stimuli, which probably leads to a better preservation or, perhaps even an accretion of lean mass during hypocaloric conditions (Garthe et al. 2011;Longland et al. 2016). ...
... The results are in accordance with other studies (Garthe et al. 2011;Longland et al. 2016;Barakat et al. 2020), suggestive of a mediating effect of RT experience on lean mass sparing during CR. Consequently, findings using RT beginners or novice athletes cannot be extrapolated to populations who are chronically adapted to RT. Beginners or novice athletes are hypersensitized to RT-induced stimuli, which probably leads to a better preservation or, perhaps even an accretion of lean mass during hypocaloric conditions (Garthe et al. 2011;Longland et al. 2016). ...
Article
Full-text available
Many sports employ caloric restriction (CR) to reduce athletes' body mass. During these phases, resistance training (RT) volume is often reduced to accommodate recovery demands. Since RT volume is a well-known anabolic stimulus, this review investigates whether a higher training volume helps to spare lean mass during CR. A total of 15 studies met inclusion criteria. The extracted data allowed calculation of total tonnage lifted (repetitions × sets × intensity load) or weekly sets per muscle group for only 4 of the 15 studies, with RT volume being highly dependent on the examined muscle group as well as weekly training frequency per muscle group. Studies involving high RT volume programs (≥ 10 weekly sets per muscle group) revealed low-to-no (mostly female) lean mass loss. Additionally, studies increasing RT volume during CR over time appeared to demonstrate no-to-low lean mass loss when compared to studies reducing RT volume. Since data regarding RT variables applied were incomplete in most of the included studies, evidence is insufficient to conclude that a higher RT volume is better suited to spare lean mass during CR, although data seem to favor higher volumes in female athletes during CR. Moreover, the data appear to suggest that increasing RT volume during CR over time might be more effective in ameliorating CR-induced atrophy in both male and female resistance-trained athletes when compared to studies reducing RT volume. The effects of CR on lean mass sparing seem to be mediated by training experience, pre-diet volume, and energy deficit, with, on average, women tending to spare more lean mass than men. Potential explanatory mechanisms for enhanced lean mass sparing include a preserved endocrine milieu as well as heightened anabolic signaling.
... The evidence described so far indicates that a combination of resistance exercise with adequate protein intake represents a viable strategy to attenuate skeletal muscle loss when in energy deficit (Carbone et al., 2019). Interestingly, it seems that these strategies may even allow for muscle mass gains in the face of an energy deficit (Josse et al., 2011;Longland et al., 2016). For example, Longland et al. (2016) reported that a high protein intake (2.4 g·kg·day −1 ) combined with high volumes of resistance and anaerobic training increased muscle mass, with concurrent fat mass loss, despite participants consuming 40% less energy than their estimated requirements throughout the 4-week intervention period. ...
... Interestingly, it seems that these strategies may even allow for muscle mass gains in the face of an energy deficit (Josse et al., 2011;Longland et al., 2016). For example, Longland et al. (2016) reported that a high protein intake (2.4 g·kg·day −1 ) combined with high volumes of resistance and anaerobic training increased muscle mass, with concurrent fat mass loss, despite participants consuming 40% less energy than their estimated requirements throughout the 4-week intervention period. It is important to highlight that the participants in these interventions were categorized as overweight or obese at baseline. ...
Article
Energy is a finite resource that is competitively distributed among the body’s systems and biological processes. During times of scarcity, energetic “trade-offs” may arise if less energy is available than is required to optimally sustain all systems. More immediately essential functions are predicted to be prioritized, even if this necessitates the diversion of energy away from – and potential downregulation of – others. These concepts are encompassed within life history theory, an evolutionary framework with considerable potential to enhance understanding of the evolved biological response to periods of energy deficiency. Skeletal muscle is a particularly interesting tissue to investigate from this perspective, given that it is one of the largest and most energetically costly tissues within the body. It is also highly plastic, responsive to a broad range of stimuli, and contributes to many essential bodily functions, e.g., mechanical, regulatory and storage. These functions may be traded off against each other during periods of energy deficiency, with the nature of the trade-off’s dependent on the characteristics of the individual and the circumstances within which the deficit occurs. In this review, we consider the skeletal muscle response to periods of energy deficiency from a life history perspective, along with how this response may be influenced by factors including sex, age, body composition, training and nutritional status.
... These results demonstrate that combining optimal EAA amounts with other nutrients may further heighten the observed responses in terms of muscle protein synthesis rates and wholebody protein metabolism [152]. In addition to these outcomes, other studies have provided support in both civilian and military contexts that adding protein to the diet (which will optimize EAA delivery) in the face of energy deficits of 30-40% can mitigate lean tissue loss and optimize loss of fat tissue [153,154]. ...
Article
Full-text available
This position stand aims to provide an evidence-based summary of the energy and nutritional demands of tactical athletes to promote optimal health and performance while keeping in mind the unique challenges faced due to work schedules, job demands, and austere environments. After a critical analysis of the literature, the following nutritional guidelines represent the position of the International Society of Sports Nutrition (ISSN). GENERAL RECOMMENDATIONS Nutritional considerations should include the provision and timing of adequate calories, macronutrients, and fluid to meet daily needs as well as strategic nutritional supplementation to improve physical, cognitive, and occupational performance outcomes; reduce risk of injury, obesity, and cardiometabolic disease; reduce the potential for a fatal mistake; and promote occupational readiness. MILITARY RECOMMENDATIONS Energy demands should be met by utilizing the Military Dietary Reference Intakes (MDRIs) established and codified in Army Regulation 40-25. Although research is somewhat limited, military personnel may also benefit from caffeine, creatine monohydrate, essential amino acids, protein, omega-3-fatty acids, beta-alanine, and L-tyrosine supplementation, especially during high-stress conditions. FIRST RESPONDER RECOMMENDATIONS Specific energy needs are unknown and may vary depending on occupation-specific tasks. It is likely the general caloric intake and macronutrient guidelines for recreational athletes or the Acceptable Macronutrient Distribution Ranges for the general healthy adult population may benefit first responders. Strategies such as implementing wellness policies, setting up supportive food environments, encouraging healthier food systems, and using community resources to offer evidence-based nutrition classes are inexpensive and potentially meaningful ways to improve physical activity and diet habits. The following provides a more detailed overview of the literature and recommendations for these populations.
... ±0.4kg), and have shown greater reductions in body fat with the addition of RT (-4.1 ±0.9kg, vs. -0.2 ±1.0kg, respectively 18 ), and in particular when caloric restriction is combined with RT and higher protein intakes 19 . When promoting fat-loss strategies, maintaining, or encouraging growth of muscle mass is of particular importance as we age, especially since muscle mass is associated with favourable glucose metabolism and is a predictor of longevity in older adults 20 . ...
Preprint
Full-text available
To date no studies have compared resistance training loading strategies combined with dietary intervention for fat loss. Thus, we performed a randomised crossover design comparing four weeks of heavier- (HL; ~80% 1RM) and lighter-load (LL; ~60% 1RM) resistance training, combined with calorie restriction and dietary guidance, including resistance trained participants (n=130; males=49, females=81). Both conditions performed low-volume, (single set of 9 exercises, 2x/week) effort matched (to momentary failure), but non-work-matched protocols. Testing was completed pre- and post-each intervention. Fat mass (kg) was the primary outcome, and a smallest effect size of interest (SESOI) was established at 3.3% loss of baseline bodyweight. Body fat percentage, lean mass, and strength (7-10RM) for chest press, leg press, and pull-down exercises were also measured. An 8-week washout period of traditional training with normal calorie interspersed each intervention. Both interventions showed small statistically equivalent (within the SESOI) reductions in fat mass (HL: -0.67 kg [95%CI -0.91 to 0.42]; LL: -0.55 kg [95%CI -0.80 to -0.31]) which were also equivalent between conditions (HL – LL: -0.113 kg [95%CI -0.437 kg to 0.212 kg]). Changes in body fat percentage and lean mass were also minimal. Strength increases were small, similar between conditions, and within a previously determined SESOI for the population included (10.1%). Fat loss reductions are not impacted by resistance training load; both HL and LL produce similar, yet small, changes to body composition over a 4-week intervention. However, the maintenance of both lean mass and strength highlights the value of resistance training during dietary intervention.
... To our knowledge, our study is the first one in Lebanon that has investigated the supplementation effect on the performance of resistance-trained individuals. Interestingly, our data confirmed that recent clinical research showing physical activity level was not associated with protein supplement frequency [43] and also reflected the findings of Longland et al. in which all measures of exercise performance improved similarly in the protein and control groups as a result of the intense exercise intervention with no effect of protein supplementation [44]. ...
Article
Full-text available
The aims of this study were first to evaluate the nutritional knowledge, perception, and source of nutrition information among resistance-trained individuals consuming protein supplements (PS), to determine whether a correlation exists between nutrition-related knowledge and the use of PS, and finally to compare the impact of PS use among participants classified as nonprotein supplement users (NPSUs) and protein supplement users (PSUs). A cross-sectional study was conducted among a highly selected group of resistance-specialized trainees (RSTs). Among the 100 RST participants recruited, the Internet and coaches were the most common source of nutritional information. About one-third of participants believed that there were no health risks after consuming PS. Both NPSU and PSU exhibit performance improvement that was significantly lessened in PSU compared to NPSU. This study demonstrated that RST may have misconceptions regarding the benefits of PS usage to increase strength. Our data also suggest a shortage of knowledge about PS and confirm that PSUs lack proper professional guidance. These findings highlight the need for proper monitoring to ensure adequate perception, awareness, and safety in the Lebanese sports sector.
... It appears that this can be prevented, or at least attenuated, by anabolic stimuli such as resistance exercise or amino acid availability, including the muscle protein synthesis-'triggering' amino acid leucine [93][94][95]97]. It has also been reported that intensive resistance training in conjunction with a high protein intake can stimulate muscle mass gains with simultaneous fat loss, despite individuals being experimentally exposed to an energy deficit of approximately 40% below estimated requirements [98]. This suggests that in certain situations the negative consequences of certain biological trade-offs may be susceptible to mitigation, given the right strategy. ...
Article
Full-text available
The energy costs of athletic training can be substantial, and deficits arising from costs unmet by adequate energy intake, leading to a state of low energy availability, may adversely impact athlete health and performance. Life history theory is a branch of evolutionary theory that recognizes that the way the body uses energy-and responds to low energy availability-is an evolved trait. Energy is a finite resource that must be distributed throughout the body to simultaneously fuel all biological processes. When energy availability is low, insufficient energy may be available to equally support all processes. As energy used for one function cannot be used for others, energetic "trade-offs" will arise. Biological processes offering the greatest immediate survival value will be protected, even if this results in energy being diverted away from others, potentially leading to their downregulation. Athletes with low energy availability provide a useful model for anthropologists investigating the biological trade-offs that occur when energy is scarce, while the broader conceptual framework provided by life history theory may be useful to sport and exercise researchers who investigate the influence of low energy availability on athlete health and performance. The goals of this review are: (1) to describe the core tenets of life history theory; (2) consider trade-offs that might occur in athletes with low energy availability in the context of four broad biological areas: reproduction, somatic maintenance , growth, and immunity; and (3) use this evolutionary perspective to consider potential directions for future research.
... Mice lose weight, develop ketosis, and produce hepatic gene expression patterns that suggest reduced de novo lipogenesis and increased fatty acid oxidation when fed a micronutrient supplemented KD that is high in fat (93.3% kcal), low in carbohydrate (1.8%), and low in protein (4.7%) [55,56]. ...
Article
Full-text available
This review aims to define the effectiveness of the ketogenic diet (KD) for the management of sarcopenic obesity. As the combination of sarcopenia and obesity appears to have multiple negative metabolic effects, this narrative review discusses the effects of the ketogenic diet as a possible synergic intervention to decrease visceral adipose tissue (VAT) and fatty infiltration of the liver as well as modulate and improve the gut microbiota, inflammation and body composition. The results of this review support the evidence that the KD improves metabolic health and expands adipose tissue γδ T cells that are important for glycaemia control during obesity. The KD is also a therapeutic option for individuals with sarcopenic obesity due to its positive effect on VAT, adipose tissue, cytokines such as blood biochemistry, gut microbiota, and body composition. However, the long-term effect of a KD on these outcomes requires further investigations before general recommendations can be made.
... Despite the differences, change in muscle surface area as measured by pQCT was positively correlated with changes in whole-body LBM (r = 0.51) for both groups combined, suggesting muscular hypertrophy may have underpinned the increases in LBM. These findings support the notion that muscle accrual can occur together with reductions in fat mass when energy deficits are combined with resistance training and protein intakes above standard daily recommendations [44][45][46][47][48]. ...
Article
Full-text available
Purpose The objective of this study was to compare the effects of 12 weeks of resistance training combined with either 5:2 intermittent fasting or continuous energy restriction on body composition, muscle size and quality, and upper and lower body strength. Methods Untrained individuals undertook 12 weeks of resistance training plus either continuous energy restriction [20% daily energy restriction (CERT)] or 5:2 intermittent fasting [~ 70% energy restriction 2 days/week, euenergetic consumption 5 days/week (IFT)], with both groups prescribed a mean of ≥ 1.4 g of protein per kilogram of body weight per day. Participants completed 2 supervised resistance and 1 unsupervised aerobic/resistance training combination session per week. Changes in lean body mass (LBM), thigh muscle size and quality, strength and dietary intake were assessed. Results Thirty-four participants completed the study (CERT = 17, IFT = 17). LBM was significantly increased (+ 3.7%, p < 0.001) and body weight (− 4.6%, p < 0.001) and fat (− 24.1%, p < 0.001) were significantly reduced with no significant difference between groups, though results differed by sex. Both groups showed improvements in thigh muscle size and quality, and reduced intramuscular and subcutaneous fat assessed by ultrasonography and peripheral quantitative computed tomography (pQCT), respectively. The CERT group demonstrated a significant increase in muscle surface area assessed by pQCT compared to the IFT group. Similar gains in upper and lower body strength and muscular endurance were observed between groups. Conclusion When combined with resistance training and moderate protein intake, continuous energy restriction and 5:2 intermittent fasting resulted in similar improvements in body composition, muscle quality, and strength. ACTRN: ACTRN12620000920998, September 2020, retrospectively registered.
Article
Objective: Body dissatisfaction elevates the risk for disordered eating behaviors. Excessive exercise is prevalent among college women and associated with harm. Risk theory posits a bidirectional relationship between risk factors for disordered eating behaviors and the behaviors themselves. This study investigated the longitudinal, reciprocal relationship between body dissatisfaction and excessive exercise. Participants and methods: College women (n = 302) assessed in August (baseline) and November (follow-up). Results: Baseline body dissatisfaction significantly predicted increases in excessive exercise endorsement at follow-up, controlling for baseline excessive exercise endorsement and body mass index (BMI). Baseline excessive exercise endorsement predicted increases in body dissatisfaction at follow-up, controlling for baseline body dissatisfaction and BMI. Conclusions: Findings support the presence of a positive feedback loop between body dissatisfaction and excessive exercise; both predict increases in risk for the other, regardless of weight status. Future research should test whether this process is ongoing and predicts further distress.
Article
Background : After a diet- or surgery induced weight loss almost 1/3 of lost weight consists of fat free mass (FFM) if carried out without additional therapy. Exercise training and a sufficient supply of protein, calcium and vitamin D is recommended to reduce the loss of FFM. Objective : To investigate the effect of exercise training, protein, calcium, and vitamin D supplementation on the preservation of FFM during non-surgical and surgical weight loss and of the combination of all interventions together in adults with obesity. Methods : A systematic review was performed with a pairwise meta-analysis and an exploratory network meta-analysis according to the PRISMA statement. Results : Thirty studies were included in the quantitative analysis. The pairwise meta-analysis showed for Exercise Training + High Protein vs. High Protein a moderate and statistically significant effect size (SMD 0.45; 95% CI 0.04 to 0.86), for Exercise Training + High Protein vs. Exercise Training a high but statistically not significant effect size (SMD 0.91; 95% CI -0.59 to 2.41) and for Exercise Training alone vs. Control a moderate but statistically not significant effect size (SMD 0.67; 95% CI -0.25 to 1.60). In the exploratory network meta-analysis three interventions showed statistically significant effect sizes compared to Control and all of them included the treatment Exercise Training. Conclusions : Results underline the importance of exercise training and a sufficient protein intake to preserve FFM during weight loss in adults with obesity. The effect of calcium and vitamin D supplementation remains controversial and further research are needed.
Article
Full-text available
Higher dietary energy as protein during weight loss results in a greater loss of fat mass and retention of muscle mass; however, the impact of protein quality on the rates of myofibrillar protein synthesis (MPS) and lipolysis, processes that are important in the maintenance of muscle and loss of fat, respectively, are unknown. We aimed to determine how the consumption of different sources of proteins (soy or whey) during a controlled short-term (14-d) hypoenergetic diet affected MPS and lipolysis. Men (n = 19) and women (n = 21) (age 35-65 y; body mass index 28-50 kg/m(2)) completed a 14-d controlled hypoenergetic diet (-750 kcal/d). Participants were randomly assigned, double blind, to receive twice-daily supplements of isolated whey (27 g/supplement) or soy (26g/supplement), providing a total protein intake of 1.3 ± 0.1 g/(kg · d), or isoenergetic carbohydrate (25 g maltodextrin/supplement) resulting in a total protein intake of 0.7 ± 0.1 g/(kg · d). Before and after the dietary intervention, primed continuous infusions of L-[ring-(13)C6] phenylalanine and [(2)H5]-glycerol were used to measure postabsorptive and postprandial rates of MPS and lipolysis. Preintervention, MPS was stimulated more (P < 0.05) with ingestion of whey than with soy or carbohydrate. Postintervention, postabsorptive MPS decreased similarly in all groups (all P < 0.05). Postprandial MPS was reduced by 9 ± 1% in the whey group, which was less (P < 0.05) than the reduction in soy and carbohydrate groups (28 ± 5% and 31 ± 5%, respectively; both P < 0.05) after the intervention. Lipolysis was suppressed during the postprandial period (P < 0.05), but more so with ingestion of carbohydrate (P < 0.05) than soy or whey. We conclude that whey protein supplementation attenuated the decline in postprandial rates of MPS after weight loss, which may be of importance in the preservation of lean mass during longer-term weight loss interventions. This trial was registered at clinicaltrials.gov as NCT01530646. © 2015 American Society for Nutrition.
Article
Full-text available
We investigated whether a training protocol that involved 3 min of intense intermittent exercise per week — within a total training time commitment of 30 min including warm up and cool down — could increase skeletal muscle oxidative capacity and markers of health status. Overweight/obese but otherwise healthy men and women (n = 7 each; age = 29±9 y; BMI = 29.8±2.7 kg/m2) performed 18 training sessions over 6 wk on a cycle ergometer. Each session began with a 2 min warm-up at 50 W, followed by 3×20 s “all-out” sprints against 5.0% body mass (mean power output: ∼450–500 W) interspersed with 2 min of recovery at 50 W, followed by a 3 min cool-down at 50 W. Peak oxygen uptake increased by 12% after training (32.6±4.5 vs. 29.1±4.2 ml/kg/min) and resting mean arterial pressure decreased by 7% (78±10 vs. 83±10 mmHg), with no difference between groups (both p<0.01, main effects for time). Skeletal muscle biopsy samples obtained before and 72 h after training revealed increased maximal activity of citrate synthase and protein content of cytochrome oxidase 4 (p<0.01, main effect), while the maximal activity of β-hydroxy acyl CoA dehydrogenase increased in men only (p<0.05). Continuous glucose monitoring measured under standard dietary conditions before and 48–72 h following training revealed lower 24 h average blood glucose concentration in men following training (5.4±0.6 vs. 5.9±0.5 mmol/L, p<0.05), but not women (5.5±0.4 vs. 5.5±0.6 mmol/L). This was associated with a greater increase in GLUT4 protein content in men compared to women (138% vs. 23%, p<0.05). Short-term interval training using a 10 min protocol that involved only 1 min of hard exercise, 3x/wk, stimulated physiological changes linked to improved health in overweight adults. Despite the small sample size, potential sex-specific adaptations were apparent that warrant further investigation.
Article
Full-text available
Background. Adequate protein ingestion-mediated stimulation of myofibrillar protein synthesis (MPS) is required to maintain skeletal muscle mass. It is currently unknown what per meal protein intake is required to maximally stimulate the response in older men and whether it differs from that of younger men. Methods. We retrospectively analyzed data from our laboratories that measured MPS in healthy older (~71 years) and younger (~22 years) men by primed constant infusion of l-ring-[13C6]phenylalanine after ingestion of varying amounts (0-40 g) of high-quality dietary protein as a single bolus and normalized to body mass and, where available, lean body mass (LBM). Results. There was no difference (p =. 53) in basal MPS rates between older (0.027±0.04%/h; means ± 95% CI) and young (0.028 ± 0.03%/h) men. Biphase linear regression and breakpoint analysis revealed the slope of first line segment was lower (p <. 05) in older men and that MPS reached a plateau after ingestion of 0.40 ± 0.19 and 0.24 ± 0.06 g/kg body mass (p =. 055) and 0.60 ± 0.29 and 0.25 ± 0.13 g/kg lean body mass (p <. 01) in older and younger men, respectively. Conclusions. This is the first report of the relative (to body weight) protein ingested dose response of MPS in younger and older men. Our data suggest that healthy older men are less sensitive to low protein intakes and require a greater relative protein intake, in a single meal, than young men to maximally stimulate postprandial rates of MPS. These results should be considered when developing nutritional solutions to maximize MPS for the maintenance or enhancement of muscle mass with advancing age. © 2014 © The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: [email protected] /* */
Article
Full-text available
Aerobic exercise is typically associated with expansion of the mitochondrial protein pool and improvements in muscle oxidative capacity. The impact of aerobic exercise intensity on the synthesis of specific skeletal muscle protein sub-fractions is not known. We aimed to study the effect of aerobic exercise intensity on rates of myofibrillar (MyoPS) and mitochondrial (MitoPS) protein synthesis over an early (0.5-4.5 h) and late (24-28 h) period during post-exercise. Using a within subject crossover design, eight males (21 ± 1 years, VO2 peak: 46.7 ± 2.0 mL•kg(-1)•min(-1)) performed two work-matched cycle ergometry exercise trials (LOW: 60 min at 30% Wmax; HIGH: 30 min at 60% Wmax) in the fasted state while undergoing a primed constant infusion of L-[ring-(13)C6]phenylalanine. Muscle biopsies were obtained at rest, and 0.5, 4.5, 24, and 28 h post-exercise to determine both the 'early' and 'late' response of MyoPS and MitoPS and the phosphorylation status of select proteins within both the Akt/mTOR and MAPK pathways. Over 24-28 h post-exercise, MitoPS was significantly greater after the HIGH vs. LOW exercise trial (P < 0.05). Rates of MyoPS were increased equivalently over 0.5-4.5 h post-exercise recovery (P < 0.05), but remained elevated at 24-28 h post-exercise only following the HIGH trial. In conclusion, an acute bout of high, but not low intensity aerobic exercise in the fasted state resulted in a sustained elevation of both MitoPS and MyoPS at 24-28 h post-exercise recovery.
Article
Full-text available
The myofibrillar protein synthesis (MPS) response to resistance exercise (REX) and protein ingestion during energy deficit (ED) is unknown. We determined, in young men (n=8) and women (n=7), protein signaling, resting post-absorptive MPS during energy balance [EB: 45 kcal•(kg FFM•d)(-1)] and after 5d of ED [30 kcal•(kg FFM•d)(-1)] as well as MPS while in ED after acute REX in the fasted state and with the ingestion of whey protein (15 and 30 g). Post-absorptive rates of MPS were 27% lower in ED than EB (P<0.001), but REX stimulated MPS to rates equal to EB. Ingestion of 15 and 30 g of protein after REX in ED increased MPS ~16 and ~34% above resting EB, (P<0.02). p70 S6K(thr389) phosphorylation increased above EB only with combined exercise and protein intake (~2-7 fold; P<0.05). In conclusion, short-term ED reduces post-absorptive MPS, however, a bout of REX in ED restores MPS to values observed at rest in EB. The ingestion of protein after REX further increases MPS above resting EB in a dose-dependent manner. We conclude that combining REX with increased protein availability after exercise enhances rates of skeletal muscle protein synthesis during short term ED and could, in the long term, preserve muscle mass.
Article
Full-text available
The purpose of this work was to determine the effects of varying levels of dietary protein on body composition and muscle protein synthesis during energy deficit (ED). A randomized controlled trial of 39 adults assigned the subjects diets providing protein at 0.8 (recommended dietary allowance; RDA), 1.6 (2×-RDA), and 2.4 (3×-RDA) g kg(-1) d(-1) for 31 d. A 10-d weight-maintenance (WM) period was followed by a 21 d, 40% ED. Body composition and postabsorptive and postprandial muscle protein synthesis were assessed during WM (d 9-10) and ED (d 30-31). Volunteers lost (P<0.05) 3.2 ± 0.2 kg body weight during ED regardless of dietary protein. The proportion of weight loss due to reductions in fat-free mass was lower (P<0.05) and the loss of fat mass was higher (P<0.05) in those receiving 2×-RDA and 3×-RDA compared to RDA. The anabolic muscle response to a protein-rich meal during ED was not different (P>0.05) from WM for 2×-RDA and 3×-RDA, but was lower during ED than WM for those consuming RDA levels of protein (energy × protein interaction, P<0.05). To assess muscle protein metabolic responses to varied protein intakes during ED, RDA served as the study control. In summary, we determined that consuming dietary protein at levels exceeding the RDA may protect fat-free mass during short-term weight loss.-Pasiakos, S. M., Cao, J. J., Margolis, L. M., Sauter, E. R., Whigham, L. D., McClung, J. P., Rood, J. C., Carbone, J. W., Combs, G. F., Jr., Young, A. J. Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: a randomized controlled trial.
Article
Strategies to enhance weight loss with a high fat-to-lean ratio in overweight/obese older adults are important since lean loss could exacerbate sarcopenia. We examined how dietary protein distribution affected muscle protein synthesis during: energy balance (EB); energy restriction (ER); and ER plus resistance training (ER+RT). A 4-wk ER diet was provided to overweight/obese older men (66 ± 4 y, 31 ± 5 kg/m(2)) who were randomized to either a balanced (BAL: 25% daily protein/meal x 4) or skewed pattern (SKEW: 7:17:72:4% daily protein/meal; n = 10/group). Myofibrillar and sarcoplasmic protein fractional synthetic rates (FSR) were measured during a 13-h primed continuous infusion of L-[ring-(13)C6] phenylalanine with BAL and SKEW pattern of protein intake in EB, after 2-wk ER, and after 2-wk ER+RT. Fed-state myofibrillar FSR was lower in ER than EB in both groups (p < 0.001), but was greater in BAL than SKEW (p = 0.014). In ER+RT, fed-state myofibrillar FSR increased above ER in both groups and in BAL was not different from EB (p = 0.903). In SKEW myofibrillar FSR remained lower than EB (p = 0.002) and lower than BAL (p = 0.006). Fed-state sarcoplasmic protein FSR was reduced similarly in ER and ER+RT compared to EB (p < 0.01) in both groups. During ER in overweight/obese older men a BAL consumption of protein stimulated the synthesis of muscle contractile proteins more effectively than traditional, SKEW distribution. Combining RT with a BAL protein distribution 'rescued' the lower rates of myofibrillar protein synthesis during moderate ER. Copyright © 2015, American Journal of Physiology - Endocrinology and Metabolism.
Article
Background Equations to estimate glomerular filtration rate (GFR) are routinely used to assess kidney function. Current equations have limited precision and systematically underestimate measured GFR at higher levels.
Obesity treatments aim to maximize fat loss, particularly abdominal or visceral fat, without compromising lean or bone mass. However, the literature contains numerous examples of obesity treatments that – in addition to fat loss – result in loss of lean mass and/or bone mass. Because of the known effects of energy restriction to increase activity of the hypothalamo-pitutiary adrenal (HPA) axis in lean humans and animals, and because increases in circulating glucocorticoid levels could potentially contribute to adverse body compositional changes with obesity treatments, we conducted a systematic PubMed search to determine whether HPA axis activation also occurs in response to energy restriction in obese humans and animals. In most studies in obese humans, short-term severe energy restriction increased circulating cortisol levels, and this response was also seen in two longer-term human studies involving severe or moderate energy restriction. These findings parallel studies on short- or long-term energy restriction in obese rodents, with most studies showing increases in circulating corticosterone concentrations, and no change or actual increases in hypothalamic expression of corticotropin-releasing hormone, urocortin 3 or their receptors. However, a significant proportion of studies involving longer-term severe or moderate energy restriction in obese humans showed no change or decreases in HPA axis function. There was variability among human studies in the duration of energy restriction and timing of the HPA axis investigations (i.e., during energy restriction, or after a period of post-restriction weight maintenance). In order to unambiguously determine changes in HPA axis function with energy restriction in obese humans, it will be important to assess HPA axis function at multiple time points