Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic Rate: A Randomized Trial

Abstract

The purpose of this study was to determine the effects of resistance training only (RT n=10), dietary intervention only (DIET n=10), resistance training plus diet (RT+DIET n=10) and control (CON n=10) on body composition and resting metabolic rate (RMR) in a cohort of 40 premenopausal female volunteers. Subjects in DIET and RT+DIET were provided with daily macronutrient and calorie goals based on DXA and RMR tests, with protein maintained at 1.4 g/kg/day. Subjects in the RT and RT+DIET groups performed a supervised progressive RT program consisting of exercises for all the major muscle groups of the body. Results showed a significant month-by-group interaction for change in fat mass with no significant linear trend for control. The three treatment groups all showed significant linear decreases in fat mass, but the slope of the decrease became progressively steeper from the RT, to DIET, to RT+DIET. A significant linear increase for lean mass was seen for resistance training-only. There was a non-significant increase in RMR in all groups from Month 0 to Month 4 but no significant month by group interaction. In conclusion, significant reductions in fat mass were achieved by all experimental groups, but results were maximized by RT+DIET. Only the RT group showed significant increases in lean mass.

Full text

“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
Note: This article will be published in a forthcoming issue of the
International Journal of Sport Nutrition and Exercise
Metabolism. This article appears here in its accepted, peer-
reviewed form; it has not been copyedited, proofed, or formatted
by the publisher.
Section: Original Research
Article Title: Resistance Training Combined With Diet Decreases Body Fat While Preserving
Lean Mass Independent of Resting Metabolic Rate: A Randomized Trial
Authors: Todd Miller1, Stephanie Mull1, Alan Albert Aragon2, James Krieger3, and Brad Jon
Schoenfeld4
Affiliations: 1George Washington University, Milken School of Public Health, Washington,
D.C. 2California State University, Northridge, CA. 3Weightology, LLC, Issaquah, WA. 4CUNY
Lehman College, Department of Health Sciences, Bronx, NY.
Running Head: Resistance training effects on fat loss
Journal: International Journal of Sport Nutrition and Exercise
Acceptance Date: August 17, 2017
©2017 Human Kinetics, Inc.
DOI: https://doi.org/10.1123/ijsnem.2017-0221

“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
RUNNING TITLE: Resistance training effects on fat loss
Resistance training combined with diet decreases body fat while preserving lean
mass independent of resting metabolic rate: A randomized trial
Todd Miller1
Stephanie Mull1
Alan Albert Aragon2
James Krieger3
Brad Jon Schoenfeld4
1George Washington University, Milken School of Public Health, Washington, D.C.
2California State University, Northridge, CA
3Weightology, LLC, Issaquah, WA, USA
4CUNY Lehman College, Department of Health Sciences, Bronx, NY
WORD COUNT: 2968
Funding: The study was funded by a grant from the Sumner M. Redstone Global Center for
Prevention and Wellness. The authors declare no conflicts of interest.
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
Abstract
The purpose of this study was to determine the effects of resistance training only (RT n=10),
dietary intervention only (DIET n=10), resistance training plus diet (RT+DIET n=10) and control
(CON n=10) on body composition and resting metabolic rate (RMR) in a cohort of 40
premenopausal female volunteers. Subjects in DIET and RT+DIET were provided with daily
macronutrient and calorie goals based on DXA and RMR tests, with protein maintained at 1.4
g/kg/day. Subjects in the RT and RT+DIET groups performed a supervised progressive RT
program consisting of exercises for all the major muscle groups of the body. Results showed a
significant month-by-group interaction for change in fat mass with no significant linear trend for
control. The three treatment groups all showed significant linear decreases in fat mass, but the
slope of the decrease became progressively steeper from the RT, to DIET, to RT+DIET. A
significant linear increase for lean mass was seen for resistance training-only. There was a non-
significant increase in RMR in all groups from Month 0 to Month 4 but no significant month by
group interaction. In conclusion, significant reductions in fat mass were achieved by all experimental
groups, but results were maximized by RT+DIET. Only the RT group showed significant increases in lean
mass.
Keywords: Body composition, strength training, fat-free mass
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
Introduction
Aerobic exercise (AE) is commonly recommended as the most effective exercise modality
for weight loss (Haskell et al., 2007). The American College of Sports Medicine (ACSM) position
stand on physical activity for weight loss recommends 150-250 minutes per week of moderate
intensity physical activity (Donnelly et al., 2009). While the ACSM promotes resistance training
(RT) as a means of increasing fat free mass, which should lead to improved body composition, it
does not promote RT for losing significant amounts of body fat. Similarly, the United States Public
Health Service physical activity guidelines for weight loss do not mention RT at all as a viable
exercise modality for weight loss. This is not surprising, as there is a paucity of research examining
the effects of RT on weight loss. Furthermore, the few studies that have explored RT for weight
loss generally show that it is ineffective (Olson, Dengel, Leon, & Schmitz, 2007; Willis et al.,
2012). Indeed, the effectiveness of any weight loss program is dependent on the size of the caloric
deficit that is created over time, and since AE generally burns more calories per unit of time than
RT (Donnelly et al., 2009), it stands to reason that AE would be the most commonly prescribed
type of exercise for losing weight. Contributing to the exclusion of RT for weight loss is a
widespread belief among dietitians, nutritionists and exercise professionals that it is not possible
to induce hypertrophy while in a caloric deficit, and since the creation of a caloric deficit is
essential for fat loss, the use of RT for muscle growth in a caloric deficit is counter-intuitive. These
beliefs continue to exist despite emerging evidence to the contrary (Josse, Atkinson, Tarnopolsky,
& Phillips, 2011; Longland, Oikawa, Mitchell, Devries, & Phillips, 2016).
RT has been shown to elevate resting metabolism for an extended period of time following
cessation of the training session (Stiegler & Cunliffe, 2006). Additionally, having a greater muscle
mass should lead to a greater resting metabolism (Gallagher et al., 1998). Unlike RT, chronic AE
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
performed in a caloric deficit (which is often the recommendation for effective weight loss) has
the potential to lead to significant decreases in muscle mass, thereby hampering improvements in
body composition (Swift, Johannsen, Lavie, Earnest, & Church, 2014). Ideally, a program
designed to improve body composition should do so through the loss of fat alone, with muscle
mass being maintained or increased. This is particularly important to premenopausal females, as
it has been reported that major weight gain occurs in women at a rate twice that of men, and is
highest in persons aged 25-34 (Williamson, Kahn, Remington, & Anda, 1990). Moreover, women
have lower baseline levels of muscle mass compared to men, and thus are at greater risk of negative
complications when muscle proteins are lost during dieting.
Several reasons could exist for the lack of effectiveness of RT reported in most weight loss
studies (Donnelly et al., 2009). Possible explanations include, but are not limited to, 1) a lack of
control and/or measurement of caloric intake; 2) failure to adjust dietary protein needs to support
muscle growth; and 3) an inadequate RT stimulus. Case studies of clients from our laboratory have
routinely demonstrated that substantial decreases in body fat can be induced with RT as the
exclusive form of exercise. Furthermore, these decreases in body fat occur with concomitant
increases in muscle mass, while in a caloric deficit.
The purpose of this study was threefold: 1) To determine whether RT combined with
dietary intervention (RT+DIET) results in greater improvements in body composition compared
with RT or DIET alone in overweight/obese premenopausal women; 2) To determine whether RT
combined with dietary intervention (RT+DIET) results in greater improvements in fat mass in the
visceral depot compared with RT or DIET alone, and; 3) To determine whether concomitant
increases in muscle mass and decreases in fat mass can occur while in a caloric deficit.
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
Methods
Subjects
Subjects were a convenience sample of 40 female volunteers (Body mass = 87.4±12.6;
Height = 165.7±7; Age = 32.3±4.8; BMI = 31.9±4.4). The sample size was based on previous
research by Jabekk (Jabekk, Moe, Meen, Tomten, & Hostmark, 2010) using change in fat mass as
the outcome measure with a target effect size difference of 0.4, alpha of 0.05 and minimum power
of 0.80. Recruitment took place from 4/1/16 to 5/14/16, and follow up took place from 8/15/16 to
9/16/16. The following inclusion criteria had to be met for participation: 1) women between 25-40
years of age; 2) regular menstrual cycle; 3) body fat >30%; 4) normally active; 5) not currently
meeting CDC physical activity guidelines; 6) no organized weight training within past 1 year; 7)
not currently dieting or food logging. Exclusion criteria included: 1) Subjects who do not have the
ability to exercise based on a Physical Activity Readiness questionnaire; 2) history of an eating
disorder; injury or medical issue that would prohibit them from resistance training; 3) pregnant or
nursing. Following recruitment, subjects were given a screening questionnaire either in-person,
electronically (via email), or verbally (via phone), in order to determine whether they were viable
candidates. Informed consent was obtained at the time of screening. The study was conducted
according to the Declaration of Helsinki, and was approved by the local University Ethics
Committee.
Random sequences were generated by the PI using a random number generator app
from https://www.random.org/. A 40 number sequence was randomly produced by the app.
Subjects were then asked by the PI to press the button on the app, and were randomly assigned to
one of 4 groups based on the following result from the app: 0-10 = Control (CON n=10); 11-20=
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
Dietary intervention only (DIET n=10); 21-30 = Resistance Training only (RT n=10); 31-40 =
Resistance Training plus Diet (RT+DIET n=10).
Testing:
Subjects meeting criteria as defined by the screening survey reported to the University lab
for secondary screening at 9:00 a.m. following an overnight fast. Body composition was then
measured via Dual Energy X-ray Absorptiometry (iDXA, Lunar; GE Medical Systems, Madison,
WI, USA). All DXA scans were analyzed using enCORE 2012 software, version 14.1 to determine
total percentage of fat and lean tissue, bone mineral content and visceral adipose tissue. Subjects
were instructed to report to the lab after an overnight fast having refrained from exercise for 48
hours and to remain normally hydrated prior to body composition and RMR assessment.
After DXA scanning, subjects underwent testing for resting metabolic rate (RMR) via
indirect calorimetry to determine daily resting caloric expenditure. Subjects sat quietly in a
reclined position and breathed normally for 10-12 minutes through a one-way valve with the nose
plugged. The subject inhaled normal room air, and exhaled air was continuously collected and sent
to a KorrReeVue indirect calorimeter (Korr Medical Technologies, Salt Lake City, UT USA).
RMR was calculated by the calorimeter (Korr ReeVue, Salt Lake City, UT), which automatically
begins collecting gas when it detects the first breath into the machine and then stops automatically
once the collection time is complete.
Follow-up DXA scans were obtained at weeks 4, 8, 12 and 16 and RMR testing was
repeated at week 16.
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
Diet
Subjects in DIET and RT+DIET groups met individually with a registered dietitian and
were given daily macronutrient and calorie goals based on their DXA and RMR tests. Calculation
of daily caloric intake was based on the Harris-Benedict equation as follows with the objective of
energy-restriction: If the RMR was within 10% of the predicted RMR, intake was set at the RMR;
if the RMR was greater than 10% over the predicted, intake was set at 10% below the measured
RMR; if the RMR was greater than 10% below the predicted, intake was set at 10% above the
measured RMR. Fat intake was set at 20% of total calories. Protein intake was calculated using a
factor of 3.1 g of protein per kg of fat free mass (Helms, Zinn, Rowlands, & Brown, 2014).
Carbohydrate made up the balance of the remaining calories.
Subjects in the DIET and RT+DIET groups began following the prescribed caloric and
macronutrient goals as established in their meeting with the dietitian within one week of the initial
meeting and continued this regimen over the entire course of the study. To track nutritional
consumption, subjects were familiarized with the usage of a phone app & website for food logging
(fatsecret.com). During the course of the study, subjects logged all of their foods daily into the
fatsecret app and the data were then analyzed to determine total energy and macronutrient intake.
Exercise
Within two weeks following initial screening, subjects in the RT and RT+DIET groups
reported to Power Train Sports and Fitness (www.powertrainsports.com) for an exercise
familiarization session. Subjects met with a certified trainer from Power Train who walked them
through the exercise program, taught proper exercise form, and establish appropriate training
loads.
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
The RT intervention began within one week following the exercise familiarization session.
All training sessions were performed under the individual supervision of a certified personal trainer
from Power Train. Training sessions continued at a rate of 2-3 per week (depending on training
phase) for 16 weeks.
The RT intervention consisted of two separate workout complexes that were alternated
every 4 weeks for the duration of the 16-week study. Exercise complex one consisted of Squats,
Romanian Deadlifts, Swiss Ball Squats, Bench Press, Lat Pulldown, Dumbbell Shoulder Press,
Incline Dumbbell Fly, Seated Row, Dumbbell Lateral Raise and Low Back Hyperextensions.
Exercise complex two consisted of Deadlifts, Leg Curls, Leg Extensions, Incline Dumbbell Press,
Close Grip Pulldowns, Arnold Press, Cable Crossover, Chest Supported Dumbbell Row, Face
Pulls and Low Back Hyperextension. Each exercise was completed for 4 sets of 10-12RM. Rest
periods between sets were between 60-90 seconds. Subjects trained 3 times per week for weeks 1-
3 of each month, then trained twice weekly during the 4th week of each month. Training loads for
a given exercise were increased when the subject could complete greater than 12 reps on the first
set, or when she could complete 12 reps on all 4 sets. Loads were progressively increased in order
to keep the RM in the 10-12 range.
Statistics
Data were modeled using a linear mixed model for repeated measures, estimated by a
restricted maximum likelihood algorithm, with drop-outs removed from the dataset. Diet
intervention (control, diet, resistance training, resistance training + diet) was included as the
between-subject factor, month (0, 1, 2, 3, 4) was included as the repeated within-subjects factor,
month x intervention was included as the interaction, and subject was included as a random effect.
In cases where significant interactions were present, linear time trends of within-group changes
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
were analyzed using linear mixed models for repeated measures. Comparisons of statistically
significant slopes for linear time trends were done using t-tests with a Holm-Bonferonni correction
for multiple comparisons.. Degrees of freedom were calculated using a Satterthwaite
approximation. Comparisons between self-reported dietary data were performed using
independent t-tests. All analyses were performed using package lmertest in R version 3.3.1 (The
R Foundation for Statistical Computing, Vienna, Austria). Effects were considered significant at
P ≤ 0.05. Data are reported as
x
± SD unless otherwise specified.
Results
A total of 31 subjects completed the study, with 9 dropouts (Control: n=8; RT: n=9; DIET:
n=9; RT+DIET: n=5). The reasons for the dropouts are as follows: 1 subject got deployed; 1
subject moved; 2 subjects suffered work-related injuries not connected to the study; and 5 subjects
ceased participation for unknown personal reasons. Outcomes for all variables are presented in
Table 1. One-way ANOVA was used to compare baseline characteristics between groups. There were no
significant differences in age (P = 0.73), body mass (P = 0.67), fat mass (P = 0.81), FFM (P = 0.63), BMC
(P = 1.0), or RMR (P = 0.83). Based on review of self-report dietary logs and estimates of energy
expenditure, diet-only achieved a daily energy restriction of ~502 kcal while training+diet achieved a daily
energy restriction of ~632 kcal.
Body Weight
There was a significant month by group interaction (P = 0.02). There was no significant
linear trend for control (β = 0.41; 95% CI = -1.08, 1.90; P = 0.58) or resistance-training-only groups
(β = 0.18; 95% CI = -0.36, 0.73; P = 0.51). There were similar significant linear decreases for the
diet-only (β = -1.35; 95% CI = -2.03, -0.67; P = 0.0004) and resistance training+diet groups (β = -
1.68; 95% CI = -2.51, -0.85; P = 0.0006). See Figure 1.
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
Percent Fat
There was a significant month by group interaction (P = 0.004). There was no significant
linear trend for control (β = 0.07; 95% CI = -0.12, 0.26; P = 0.45). There were similar significant
linear decreases for the diet-only (β = -0.40; 95% CI = -0.54, -0.26; P = 0.0), resistance-training
only (β = -0.38; 95% CI = -0.57, -0.19; P = 0.0003), and resistance-training+diet groups (β = -
0.53; CI = -0.74, -0.33; P < 0.0001). See Figure 2.
Fat Mass
There was a significant month by group interaction (P = 0.003). There was no significant
linear trend for control (β = 0.38; 95% CI = -0.62, 1.37; P = 0.46). The three treatment groups all
showed significant linear decreases in fat mass, but the slope of the decrease became progressively
steeper from the resistance-training only group, to the diet-only group, to the resistance-
training+diet group (resistance training-only: β = -0.58; 95% CI = -1.02, -0.14; P = 0.01; diet-
only: β = -1.35; 95% CI = -1.87, -0.83; P = 0.0; resistance training+diet: β = -1.80; 95% CI = -
2.43, -1.17; P < 0.0001). See Figure 3. When comparing the three statistically significant slopes
for fat mass using t-tests corrected for multiple comparisons by Holm-Bonferroni, resistance
training+diet showed a significantly greater slope than resistance training-only (P = 0.0019 tested
at 0.017 Holm-Bonferonni threshold); diet-only showed a non-significantly greater slope than
resistance training-only (P = 0.027 tested at 0.025 Holm-Bonferonni threshold). There was no
significant difference between resistance training+diet and diet-only (P = 0.29).
Lean Mass
There was nearly a significant month by group interaction (P = 0.052). There was no
significant linear trend for control (β = 0.03; 95% CI = -0.52, 0.57; P = 0.93), diet-only (β = -0.004;
CI = -0.30, 0.29; P = 0.98), or resistance training+diet (β = 0.11; 95% CI = -0.40, 0.62; P = 0.67).
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
There was a significant linear increase for resistance training-only (β = 0.76; 95% CI = 0.32, 1.2;
P = 0.002). See Figure 4.
Bone Mineral Content
There was no significant month by group interaction (P = 0.077). There were no significant
linear trends for any groups (Control: β = -0.003; 95% CI = -0.01, 0.01; P = 0.60; Diet-Only: β =
-0.01; 95% CI = -0.03, 0.004; P = 0.16; Resistance Training-Only: β = 0.009; 95% CI = -0.004,
0.02; P = 0.17; Resistance Training+Diet: β = 0.008; 95% CI = -0.01, 0.03; P = 0.46).
VAT
There was no significant month by group interaction (P = 0.20), group effect (P = 0.86), or
month effect (P = 0.14) for VAT.
Resting Metabolic Rate (RMR)
There was no significant month by group interaction (P = 0.79) or group effect (P = 0.76).
There was a non-significant (P = 0.092) increase in RMR in all groups from Month 0 to Month 4.
There were no significant interactions or main effects for RMR as a percentage of the predicted
value, with p-values ranging from 0.28 – 0.58 (pertaining to both the interaction term in the model, and
the two main effects)
Self-Reported Dietary Data
Self-reported dietary data are shown in Table 2. There were no significant differences
between the diet-only and diet+training groups for self-reported calorie intake (P = 0.49),
carbohydrate intake (P = 0.31), fat intake (P = 0.71), or protein intake (P = 0.62). There were also
no significant differences between groups for percentage of goals for calorie intake or
macronutrients (P = 0.23 – 0.75).
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
Group dietary time trends are shown in Table 2. There was no significant month by group
interaction for calories (P = 0.40), protein (P = 0.77), or carbohydrate (P = 0.44). There were no
main effects of group for calories (P = 0.45), protein (P = 0.44), or carbohydrate (P = 0.31), nor
were there main effects of time for calories (P = 0.23), protein (P = 0.09), or carbohydrate (P =
0.41). There was a significant month by group interaction for fat (P = 0.02). There was a significant
linear trend for fat to decrease in the diet only group (β = -1.20; CI = -2.30, -0.10; P = 0.04),
whereas there was no trend in the diet and training group (P = 0.51).
Discussion
The study produced several notable findings. First, while reductions in fat mass were
achieved by all experimental groups, results were maximized by combining of RT and diet.
Second, only the RT group showed significant increases in lean mass; combining RT with diet
attenuated these increases. Finally, RMR remained unchanged over the course of the study period
for all conditions; changes in lean mass did not significantly affect this outcome.
The well-established negative effects of excess body fat on health and wellness underscore
the importance of determining effective strategies for weight loss. All treatments produced
significant reductions in fat mass over the 16 week study period, with the exception of RT-only,
which showed a decrease in fat mass at months 1-3, but an increase in fat mass at month 4. These
losses persisted in a linear fashion across each month of the study, with the slope of the decrease
becoming progressively steeper from RT-only to DIET-only to RT+DIET. Although RT-only did
not receive any nutritional prescription and were told not to make any modifications to their usual
diet, this group apparently was in a hypocaloric state during the initial 3 months of the trial, perhaps
inspired by a desire to realize additional benefits upon initiating an exercise program. The increase
in fat mass at the fourth month may have reflected a lapse in eating restraint due to an absence of
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
dietary programming. These results reinforce the fact that nutritional intervention combined with
exercise is paramount with respect to fat loss, with exercise providing a supplemental but important
role in the process. Illustrating this point, a systematic review and meta-analysis by Clark (Clark,
2015) found that diet plus RT or a combination of RT and AE had a greater impact on improving
body composition than diet alone. In a study specific to resistance training, Bouchard et al
(Bouchard, Soucy, Senechal, Dionne, & Brochu, 2009) compared the effects of caloric restriction
(CR), resistance training (RT), or a combination of the two (CR + RT) in a cohort of obese
postmenopausal women. Significant fat loss occurred in CR and CR + RT, but not RT alone.
The maintenance of high levels of muscle mass has implications on physical function, and
plays a role in the prevention of common pathologic conditions and chronic diseases (Wolfe,
2006). In this regard, only the RT group showed a significant increase in lean mass, with subjects
gaining 2.2 kg over the 16 week study period. In the absence of caloric restriction, lean mass gains
via resistance training are expected, especially in untrained subjects. In an investigation with a
similar subject profile (obese women age 20-40 yrs in nondieting conditions), Jabekk et al (Jabekk
et al., 2010) reported that the nondieting control group gained 1.5 kg FFM during 10 weeks of RT.
Assuming the same rate of gain extended another 6 weeks to match the length of the present study,
this would have amounted to 2.4 kg FFM; which is consistent with the gain of 2.2 kg seen in the
present study. In contrast with recent studies (Josse et al., 2011; Longland et al., 2016), the
RT+DIET group did not show significant increases in lean mass over the duration of the study.
However, it should be noted that there was a linear increase over the first 12 weeks of the study,
with an apparent loss of these gains during the final month. The reason for this finding is not
readily apparent. An additional consideration is that water is the predominant and most widely
fluctuating component of FFM due to varying glycogen concentrations, electrolyte balance
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Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
influencing hydration, and other factors. Therefore, increases in FFM are not necessarily
accompanied by directly proportional increases in contractile protein and do not necessarily reflect
gains in muscle mass.
Interestingly, the diet-only group did not lose any FFM over the 16 week intervention
period. Research generally shows a loss of lean tissue concomitant to a caloric deficit. It is
conceivable that the high-protein content of the diet (3.1 g/kg/FFM) helped to offset any such
losses. In support of this, a systematic review by Helms et al (Helms et al., 2014) reported that
lean, resistance-trained subjects in hypocaloric conditions required a protein intake of 2.3-3.1 g/kg
FFM in order to maximally protect against lean tissue losses. In addition, the present study did not
involve particularly aggressive caloric restriction (1419 & 1505 kcal/day in DIET and RT + DIET,
respectively). Despite rigorous efforts to ensure compliance to the diet (i.e. weekly review of food
logs, ongoing email support for dietary tracking, and monthly meetings with the dietician to answer
any diet-related questions), there nevertheless is the possibility of under-reporting of caloric intake.
Lichtman et al (Lichtman et al., 1992) found that obese subjects under-reported their intake by an
average of 47% (a group mean of 1053 kcal/day). Thus, in addition to the non-aggressively
prescribed caloric deficit, the potential for under-reporting total energy combined with the high
protein intake target could have spared FFM.
There were no significant changes in RMR noted from pre- to post-study in any of the
conditions studied. Our results on the topic concur with the body of literature, which shows that
changes in lean mass do not necessarily parallel changes in RMR (Stiegler & Cunliffe, 2006).
Although there is a clear metabolic cost of maintaining lean mass, the actual energy expenditure
associated with skeletal muscle is rather low, estimated at only ~13 kcal/kg per day (Wang et al.,
2011). Aristizabal et al. (Aristizabal et al., 2015) recently investigated the possibility of estimating
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
RMR responses in resistance-training subjects via DXA-measured changes in FFM. Although
there was a large degree of interindividual variability, 9 months of resistance training and
supplementation with either protein or carbohydrate increased RMR by an average of 5%, and
FFM (among other factors) was positively correlated with this small but significant increase. In
light of this finding, it is possible that the present study would need a longer duration to detect
significant changes in RMR.
Our study had several notable limitations that must be considered when making evidence-
based inferences from the data. First, although DXA is a well-established modality for estimating
body composition, the measurement of lean mass is specific to all non-fat and bone-free
components, and thus does not necessarily reflect changes in skeletal muscle. Second, given that
the subjects were premenopausal women, menstrual changes may have altered observed changes
in body composition. Third, the findings are specific to obese, premenopausal women and cannot
necessarily be generalized to other populations. Finally, the sample size was rather small, thereby
limiting statistical power for probability assessment.
Conclusion
Findings of this study indicate that a total-body RT program combined with a caloric deficit
is a viable strategy for reducing body fat while preserving lean mass in obese, premenopausal
women. Positive results do not appear to be related to increases in RMR. Given the health-related
implications for carrying excess body fat, these findings indicate that diet is the paramount
consideration for combating obesity and combining nutritional prescription with RT appears to
help optimize changes in body composition.
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
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Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
Figure 1. Effect of experimental conditions on changes in body weight in Diet Only, Resistance
Training Only, and Resistance Training + Diet groups for each month across the duration of the
study. * denotes significant linear trend
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
Figure 2. Effect of experimental conditions on changes in percent body fat in Diet Only,
Resistance Training Only, and Resistance Training + Diet groups for each month across the
duration of the study. * denotes significant linear trend
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
Figure 3. Effect of experimental conditions on changes in fat mass in Diet Only, Resistance
Training Only, and Resistance Training + Diet groups for each month across the duration of the
study. * denotes significant linear trend
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
Figure 4. Effect of experimental conditions on changes in lean mass in Diet Only, Resistance
Training Only, and Resistance Training + Diet groups for each month across the duration of the
study. * denotes significant linear trend
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
TABLE 1: Outcomes for all variables across time (mean ± SD)
Outcome
Group
Month 0
Month 1
Month 2
Month 3
Month 4
Body Weight
(kgs)*
Control
86.0 ± 15.2
86.8 ± 18.0
Diet**
82.0 ± 11.3
80.9 ± 10.5
80.3 ± 10.3
79.5 ± 10.3
79.7 ± 10.2
Training
85.9 ± 15.3
86.1 ± 15.2
86.1 ± 15.3
85.8 ± 15.3
88.3 ± 16.0
Training +
Diet**
91.1 ± 4.4
90.1 ± 4.5
89.5 ± 4.6
88.8 ± 3.8
88.0 ± 4.0
Percent Fat*
Control
43.0 ± 6.0
43.3 ± 6.5
Diet**
44.0 ± 4.4
43.3 ± 4.5
42.9 ± 4.2
42.7 ± 4.0
42.2 ± 4.0
Training**
44.3 ± 6.0
43.4 ± 6.0
42.9 ± 5.7
42.8 ± 5.9
43.1 ± 6.6
Training +
Diet**
45.3 ± 4.7
44.2 ± 4.7
43.8 ± 4.6
42.9 ± 4.9
43.3 ± 4.5
Fat Mass
(kgs)*
Control
37.5 ± 10.5
38.1 ± 12.1
Diet**
36.4 ± 7.9
35.2 ± 7.4
34.7 ± 7.0
34.1 ± 7.0
33.9 ± 6.8
Training
38.6 ± 11.0
37.8 ± 10.7
37.4 ± 10.5
37.3 ± 11.0
38.6 ± 11.7
Training +
Diet**
41.3 ± 5.1
39.9 ± 5.0
39.2 ± 5.1
38.2 ± 5.2
38.0 ± 4.4
Lean Mass
(kgs)
Control
45.9 ± 6.9
46.0 ± 8.0
Diet
43.0 ± 4.6
43.0 ± 4.6
43.0 ± 4.7
42.7 ± 4.5
43.1 ± 4.6
Training**
44.7 ± 6.4
45.6 ± 6.7
46.0 ± 6.7
45.8 ± 6.0
46.9 ± 6.5
Training +
Diet
47.1 ± 4.5
47.6 ± 4.5
47.6 ± 4.4
48.0 ± 4.3
47.1 ± 4.7
BMC (kgs)
Control
2.7 ± 0.3
2.7 ± 0.3
Diet
2.7 ± 0.4
2.7 ± 0.4
2.7 ± 0.4
2.7 ± 0.4
2.7 ± 0.5
Training
2.7 ± 0.5
2.7 ± 0.4
2.7 ± 1.0
2.7 ± 0.4
2.7 ± 0.5
Training +
Diet
5.9 ± 0.4
5.9 ± 0.3
5.9 ± 0.4
5.9 ± 0.4
5.9 ± 0.3
VAT (kgs)
Control
0.9 ± 0.4
1.0 ± 0.5
Diet
0.8 ± 0.5
0.7 ± 0.5
0.7 ± 0.4
0.7 ± 0.4
0.7 ± 0.4
Training
0.8 ± 0.5
0.8 ± 0.5
0.8 ± 0.6
0.8 ± 0.5
0.9 ± 0.6
Training +
Diet
0.9 ± 0.4
0.9 ± 0.4
0.9 ± 0.4
0.8 ± 0.4
0.8 ± 0.3
RMR (kcal/d)
Control
1494 ± 193
1624 ± 301
Diet
1484 ± 232
1563 ± 216
Training
1525 ± 174
1544 ± 190
Training +
Diet
1595 ± 334
1673 ± 175
* = significant group x month interaction (P < 0.05)
** = significant linear time trend within group (P < 0.05)
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“Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic
Rate: A Randomized Trial” by Miller T et al.
International Journal of Sport Nutrition and Exercise Metabolism
© 2017 Human Kinetics, Inc.
TABLE 2: Self-Reported Dietary Intake of Energy and Macronutrients for Each Month of the
Study (mean ± SD)
Aggregate Dietary Data
Diet Only
Diet + Training
Kcal
1419 ± 183
1505 ± 223
Protein (g)
114 ± 21
120 ± 23
Carbohydrate (g)
145 ± 24
159 ± 22
Fat (g)
42 ± 5
41 ± 7
Dietary Data by Month
Month 1
Month 2
Month 3
Month 4
Kcal
Diet
1439 ± 104
1441 ± 179
1397 ± 294
1401 ± 186
Diet+Training
1467 ± 319
1574 ± 211
1533 ± 219
1448 ± 198
Protein (g)
Diet
108 ± 17
116 ± 20
110 ± 34
108 ± 23
Diet+Training
118 ± 27
130 ± 20
122 ± 27
112 ± 29
arbohydrate (g)
Diet
147 ± 18
147 ± 27
143 ± 32
143 ± 25
Diet+Training
154 ± 36
165 ± 23
164 ± 32
154 ± 25
Fat (g) *
Diet**
46 ± 5
42 ± 6
40 ± 8
42 ± 5
Diet+Training
39 ± 8
42 ± 8
42 ± 7
41 ± 6
* = significant group x month interaction (P < 0.05)
** = significant linear time trend within group (P < 0.05)
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