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A whey-protein supplement increases fat loss and spares lean muscle in obese subjects: A randomized human clinical study

Authors:
  • Frestedt Incorporated
  • Glanbia Nutritionals

Abstract and Figures

This study evaluated a specialized whey fraction (Prolibratrade mark, high in leucine, bioactive peptides and milk calcium) for use as a dietary supplement to enhance weight loss. This was a randomized, double-blind, parallel-arm, 12-week study. Caloric intake was reduced 500 calories per day. Subjects consumed Prolibra or an isocaloric ready-to-mix beverage 20 minutes before breakfast and 20 minutes before dinner. Body fat and lean muscle tissue were measured by dual-energy x-ray absorptiometry (DEXA). Body weight and anthropometric measurements were recorded every 4 weeks. Blood samples were taken at the beginning and end of the study. Statistical analyses were performed on all subjects that completed (completer analysis) and all subjects that lost at least 2.25 kg of body weight (responder analysis). Within group significance was determined at P < 0.05 using a two-tailed paired t-test and between group significance was determined using one way analysis of covariance with baseline data as a covariate. Both groups lost a significant amount of weight and the Prolibra group tended to lose more weight than the control group; however the amount of weight loss was not significantly different between groups after 12 weeks. Prolibra subjects lost significantly more body fat compared to control subjects for both the completer (2.81 vs. 1.62 kg P = 0.03) and responder (3.63 vs. 2.11 kg, P = 0.01) groups. Prolibra subjects lost significantly less lean muscle mass in the responder group (1.07 vs. 2.41 kg, P = 0.02). The ratio of fat to lean loss (kg fat lost/kg lean lost) was much larger for Prolibra subjects for both completer (3.75 vs. 1.05) and responder (3.39 vs. 0.88) groups. Subjects in both the control and treatment group lost a significant amount of weight with a 500 calorie reduced diet. Subjects taking Prolibra lost significantly more body fat and showed a greater preservation of lean muscle compared to subjects consuming the control beverage. Because subjects taking Prolibra lost 6.1% of their body fat mass, and because a 5% reduction of body fat mass has been shown to reduce the risk of obesity related disease, the results have practical significance.
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BioMed Central
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Nutrition & Metabolism
Open Access
Research
A whey-protein supplement increases fat loss and spares lean
muscle in obese subjects: a randomized human clinical study
Joy L Frestedt
1
, John L Zenk
1
, Michael A Kuskowski
2
, Loren S Ward*
3
and
Eric D Bastian
3
Address:
1
Minnesota Applied Research Center (MARC), Edina, MN, USA,
2
Geriatric Research Education and Clinical Center (GRECC), Veterans
Administration Medical Center, Minneapolis, MN, USA and
3
Glanbia Research and Development Center, Twin Falls, ID, USA
Email: Joy L Frestedt - frest001@umn.edu; John L Zenk - jzenk@humaneticscorp.com; Michael A Kuskowski - mike@james.psych.umn.edu;
Loren S Ward* - lward@glanbiausa.com; Eric D Bastian - ebastian@glanbiausa.com
* Corresponding author
Abstract
Background: This study evaluated a specialized whey fraction (Prolibra™, high in leucine,
bioactive peptides and milk calcium) for use as a dietary supplement to enhance weight loss.
Methods: This was a randomized, double-blind, parallel-arm, 12-week study. Caloric intake was
reduced 500 calories per day. Subjects consumed Prolibra or an isocaloric ready-to-mix beverage
20 minutes before breakfast and 20 minutes before dinner. Body fat and lean muscle tissue were
measured by dual-energy x-ray absorptiometry (DEXA). Body weight and anthropometric
measurements were recorded every 4 weeks. Blood samples were taken at the beginning and end
of the study. Statistical analyses were performed on all subjects that completed (completer analysis)
and all subjects that lost at least 2.25 kg of body weight (responder analysis). Within group
significance was determined at P < 0.05 using a two-tailed paired t-test and between group
significance was determined using one way analysis of covariance with baseline data as a covariate.
Results: Both groups lost a significant amount of weight and the Prolibra group tended to lose
more weight than the control group; however the amount of weight loss was not significantly
different between groups after 12 weeks. Prolibra subjects lost significantly more body fat
compared to control subjects for both the completer (2.81 vs. 1.62 kg P = 0.03) and responder
(3.63 vs. 2.11 kg, P = 0.01) groups. Prolibra subjects lost significantly less lean muscle mass in the
responder group (1.07 vs. 2.41 kg, P = 0.02). The ratio of fat to lean loss (kg fat lost/kg lean lost)
was much larger for Prolibra subjects for both completer (3.75 vs. 1.05) and responder (3.39 vs.
0.88) groups.
Conclusion: Subjects in both the control and treatment group lost a significant amount of weight
with a 500 calorie reduced diet. Subjects taking Prolibra lost significantly more body fat and showed
a greater preservation of lean muscle compared to subjects consuming the control beverage.
Because subjects taking Prolibra lost 6.1% of their body fat mass, and because a 5% reduction of
body fat mass has been shown to reduce the risk of obesity related disease, the results have
practical significance.
Published: 27 March 2008
Nutrition & Metabolism 2008, 5:8 doi:10.1186/1743-7075-5-8
Received: 19 October 2007
Accepted: 27 March 2008
This article is available from: http://www.nutritionandmetabolism.com/content/5/1/8
© 2008 Frestedt et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0
),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Introduction
The growing obesity epidemic is a world wide concern [1].
Obesity contributes to health issues that result from carry-
ing increased fat mass such as sleep apnea, osteoarthritis
and joint and skin abnormalities and health issues that
result from the metabolic effect of fat cells such as type 2
diabetes, insulin resistance, metabolic syndrome, hyper-
tension, nonalcoholic fatty liver disease, heart disease,
gallbladder disease and cancer [2,3]. Decreasing body fat
mass in humans significantly reduces health issues that
arise from increased body fat [2,3].
An effective approach to weight management is to
increase dietary protein or change the ratio of carbohy-
drate to protein in the diet [4]. A low carbohydrate to pro-
tein ratio (<2) with greater than 100 grams of protein per
day in the form of meats, eggs, cheese, milk and nuts
increased fat loss and retained lean muscle during dieting
[5-8]. Layman et al. [5] studied body composition and
weight loss in women who consumed a hypocaloric diet
with a 1.4 or a 3.5 carbohydrate to protein ratio. Weight
loss was not significantly different between groups but fat
loss significantly increased for those consuming the high
protein diet (~125 g/day). Skov et al. [8] measured the
effect of carbohydrate to protein ratio on body composi-
tion in a hypocaloric study. The treatment group con-
sumed an ad libitum fat-reduced diet with a 1.9
carbohydrate to protein ratio and the control group con-
sumed an ad libitum fat reduced diet with a 4.9 carbohy-
drate to protein ratio. The weight and fat losses over six
months significantly increased in the high protein group
compared to the control group (8.0 kg versus 5.1 kg for
weight loss and 7.6 versus 4.3 kg for fat loss).
Increasing fat loss through dietary changes helps retain
lean muscle mass. Retaining lean muscle translates into
increased body strength, increased basal metabolic rate
and increased bone strength [9]. The retention of lean
muscle during weight loss may be related to the leucine's
ability to stimulate muscle synthesis [10]. The post-pran-
dial rate of protein synthesis also depends on the speed of
protein absorption. Fast absorbing protein has an ana-
bolic effect [11]. The high leucine content (50–75% more
than other common food proteins) of whey proteins [10]
coupled with fast absorption [11] make whey protein
ideal as a protein supplement during weight loss.
Whey proteins also modulate several hormones that influ-
ence body composition. Short term acute studies with
whey proteins corroborate the body composition changes
seen with longer term feeding studies. Whey protein iso-
late (75 grams per dose) was evaluated [12] for its impact
on obesity-related hormones in an acute (5 hour) protein
ingestion in overweight and obese women with polycystic
ovary syndrome (PCOS). The acute hormonal response
showed significantly lower hyperinsulinemia (less lipo-
genesis), lower cortisol levels (lean muscle preservation)
and increased ghrelin release (satiety enhancement).
Another dietary approach to decrease body fat is to
increase dietary calcium. Increasing dietary calcium
decreased body fat and improved body composition in
several studies [13-20]. Two different mechanisms have
been suggested and include the formation of calcium
soaps and decreased intestinal absorption of fat [21,22] or
an indirect hormonal mechanism [19] that increases
lipolysis in adipocyte tissue.
Several studies [23,24] show that calcium supplementa-
tion with dairy products may arrest bone resorption dur-
ing weight loss, provide stronger bones and reduce the
potential for fractures after weight loss particularly in
women over 65. Women over 65 who lose weight are at
least 1.8 times more likely to have a bone fracture com-
pared to counterparts that do not lose weight [25]. Other
benefits of dairy minerals include research showing that
milk minerals decrease co-morbidities that are associated
with obesity such as hypertension [26] and stroke [27].
This research study was designed to test the impact of Pro-
libra, a dairy-derived ingredient containing whey pro-
teins, peptides and milk minerals, on weight loss, fat loss
and lean muscle retention in obese individuals. Our
hypothesis was that by purifying the active ingredients
from milk (high leucine proteins, peptides and milk min-
erals) a supplement could be developed that would have
a positive impact on fat loss, aid in retaining lean muscle
and retain bone mineral content without needing to
increase dietary protein intake above the recommended
RDI (0.8 g/kg/day). The objective of the trial was to eval-
uate the effect of a Prolibra beverage on weight loss, body
composition and anthropometric measurements over a
12-week period compared to a control beverage.
Methods
Subjects
One-hundred and fifty-eight subjects were recruited for
this study through local advertising. Subjects were 25–50
years old with a body mass index (BMI) of 30–42 kg/m
2
.
Subjects who were pregnant, lactating or at risk for becom-
ing pregnant as well as subjects with digestive disorders,
diabetes, hypertension, cardiovascular disease, eating dis-
orders or other illnesses were excluded from the study.
Subjects consuming more than one dairy serving per day
were counseled to limit dairy intake to one serving per
day. The Quorum Institutional Review Board (Seattle,
WA) approved the study protocol, informed consent
form, subject informational materials and advertisements
before subject recruitment. Each subject provided volun-
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tary written consent before initiating any clinical trial
related activities.
Diets
Subjects recorded their food intake (without changing
their usual dietary regimen) for five days during two
weeks (i.e. Monday, Wednesday, Friday, Tuesday, and
Thursday). Subjects returned to the clinic for diet assess-
ment and were randomly assigned to a control group (n =
53) or to the Prolibra group (n = 53) or a third experimen-
tal arm (n = 52, data not shown). This report describes the
results from the control group versus the Prolibra group.
Subjects were assigned a diet plan with a certain number
of servings for various food groups similar to the standard
paradigm set by the American Heart Association [28].
Subjects were counseled to reduce caloric intake by 500
calories per day. Individual diets were assigned based on
the subject's Resting Metabolic Rate (RMR) using the for-
mula: RMR × 1.3 – 500. Resting Metabolic Rate was meas-
ured by indirect calorimetry using an open-circuit
ventilated-hood system. Except for water, subjects fasted
for 12 hours prior to the RMR measurements. Subjects
rested for 15 minutes prior to RMR measurement and
were then placed alone in a recumbent position in a quiet,
dimly lit, temperature-controlled room where they under-
went 25 minutes of respiratory sampling under the hood.
The metabolic monitor recorded energy expenditure read-
ings in one-minute intervals. The final 20 minutes of read-
ings were averaged to arrive at the RMR for that visit. To
avoid over estimating energy expenditure, the RMR data
were reviewed together with the 2-week baseline diet dia-
ries and subjects were interviewed regarding their physical
activity levels before prescribing the diet. All subjects were
counseled to keep their physical activity level constant
throughout the trial. Subjects were instructed to restrict
dairy consumption to 1 serving per day and total cal-
cium intake to less than 500 mg/day.
The composition of the planned diet was approximately
55% of calories as carbohydrate, 15% as protein, and 30%
as fat. These percentages were distributed into 3 meals and
2 snacks per day. The servings were represented in terms
of exchanges and a list was provided for the subject out-
lining appropriate portion sizes and serving suggestions.
A sample diet showing the distribution of servings from
each macronutrient group was discussed with each sub-
ject. A broad range of diet instruction sheets (including
1000, 1200, 1400, 1600, 1800, 2000, 2200, and 2400 cal-
orie diets) were used to direct subjects to comply with
their specific diet. Subjects were also given diet diaries to
record their food consumption along with reading mate-
rials including a grocery foods list, tips for dining out and
tips for dieting success. Subjects were instructed that the
anticipated weight loss was one pound per week on this
diet plan. The composition of the diet combined with the
Prolibra supplement produced a carbohydrate to protein
ratio of 2.4 in the Prolibra group and a carbohydrate to
protein ratio of 3.6 in the control group. Table 1 contains
the baseline characteristics for both groups.
Subjects completed diet diaries on at least five days each
month and clinic staff evaluated and discussed the diet
dairies at each visit with the subject to assist each subject
in controlling their calories, physical activity and calcium
intake. Concerns and questions were addressed and eating
patterns were discussed.
Measurements
Subjects were weighed at weeks 0, 4, 8 and 12 in a paper
exam gown using a 752 Healthometer Professional-
752KL digital scale (Sunbeam, Boca Raton, Fl) and waist
and hip circumferences as well as vital signs were meas-
ured at weeks 0, 4, 8, and 12. Total body fat, lean muscle
tissue and trunk fat were measure by dual energy x-ray
absorptiometry (Lunar Prodigy Advance Plus, General
Electric, Madison, WI) at weeks 0 and 12. Resting meta-
bolic rate was determined by indirect calorimetry using a
TrueOne 2400 Metabolic Measurement system (Parvo
Medics Inc., Yorba Sandy, Utah). Total body water was
measured using a Quantum II bioelectric impedance anal-
ysis instrument (RJL Systems, Clinton Township, MI).
Venous blood samples were collected from each subject at
weeks 0 and 12 and a chemistry profile, lipid profile, insu-
lin and complete blood counts were obtained (Quest
Diagnostics Laboratory, Minneapolis, MN). Waist and hip
circumference measurements were also performed with
the subjects in an exam gown using a Tech-Med (model
Table 1: Subject characteristics at baseline (mean ± standard error).
Control group (n = 28) Prolibra group (n = 31) Control group (n = 19) Prolibra group (n = 23)
Completers Responders
Age (years) 42.0 ± 1.2 43.6 ± 1.1 42.5 ± 1.5 43.6 ± 1.0
Height (cm) 166.4 ± 1.4 166.6 ± 1.3 167.2 ± 1.6 166.7 ± 1.5
Weight (kg) 98.0 ± 2.2 98.9 ± 2.1 100.6 ± 3.0 100.0 ± 2.8
BMI (kg/m2) 35.4 ± 0.7 35.7 ± 0.7 35.9 ± 0.8 35.9 ± 0.8
Waist circumference (cm) 101.1 ± 2.0 105.1 ± 1.9 102.0 ± 1.1 103.8 ± 1.9
Hip circumference (cm) 120.3 ± 1.9 120.1 ± 1.8 122.7 ± 2.2 121.0 ± 2.3
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#4414) measuring tape according to the following tech-
nique: waist circumference was obtained at the midpoint
between the level of the lowest rib and the top of the ante-
rior iliac crest and hip circumference was obtained at the
level of largest diameter below the anterior iliac crest.
Supplements
Each subject was instructed to consume one supplement
20 minutes before breakfast and one supplement 20 min-
utes before dinner. The supplement was in the form of a
sachet containing a chocolate flavored ready to mix drink
and each subject was provided a hand shaker for mixing
the drink. The product was mixed with 8 oz of water in a
hand shaker and then consumed. Total protein in the sup-
plements was measured using Kjeldahl (AOAC 945.01)
with a conversion factor of 6.38. Total carbohydrate was
measured using the phenol-sulfuric acid method [29].
Total ash was measured using AOAC 954.46. Calcium
content was measured using AOAC 965.09/975.03AA.
Total fat was measured using the Mojonneir method
(AOAC 989.05). The nutritional characteristics of the
unflavored Prolibra are found in Table 2. The Prolibra
supplement contained 10 grams of protein per serving as
a combination of intact whey protein and peptides. It also
contained minerals that were purified from milk. The con-
trol group received an iso-caloric beverage containing
maltodextrin. Compliance with the study protocol was
assessed by supplement count and diet diary review. Sub-
jects were also contacted by telephone between visits to
review diet and supplement compliance and to answer
any questions.
Statistical analysis
The statistical analysis was generated using SAS (Copy-
right, SAS Institute Inc. Cary, NC, USA.). Baseline differ-
ences were determined using one-way ANOVA.
Differences between groups at week 12 were determined
using one-way analysis of covariance with the baseline
data as the covariate (ANCOVA). If a significant group
effect was found, post hoc two-group pairwise compari-
sons based on estimated marginal means were done using
the Least Significant Difference (LSD) test. Differences
within groups were determined using a two-sided paired
t-test. Both a completer analysis and responder analysis
was performed. Those that completed the study were
included in the completer analysis and subjects that lost at
least 2.25 kg of body weight were included in the
responder analysis.
Results
Subject attrition
Forty-seven (47) subjects withdrew from the study.
Among the 22 subjects who withdrew from the treatment
group: 2 subjects were withdrawn due to the development
of an intercurrent illness/medical condition (one had cel-
lulitis secondary to a bug bite and one persistent pyelone-
phritis); 1 subject withdrew because she felt the test article
had unpleasant properties; 10 subjects withdrew for clini-
cal trial related reasons including that the trial activities
took too much time or their personal situation changed at
home or at work; 3 subjects were withdrawn for failure to
maintain adequate compliance with the clinical trial pro-
tocol; 1 subject did not meet the entry criteria; 1 subject
was diagnosed with hypothyroidism during the trial and
was withdrawn because they used a non-approved medi-
cation during the trial (Levothyroxine); 1 subject was
withdrawn because she had received the test articles but
returned all packages unused; and 3 subjects were lost to
follow-up. Among the 25 subjects who withdrew from the
placebo group: 12 withdrew for clinical trial related rea-
sons including that the trial activities took too much time
or their personal situation changed at home or at work; 9
were withdrawn for failure to maintain adequate compli-
ance with the clinical trial protocol; 1 subject was with-
drawn because she no longer met inclusion criteria after a
15 pound weight fluctuation between the first and second
visits; 1 subject was withdrawn because she became preg-
nant during the trial, and 2 subjects were lost to follow-
up.
Dietary analysis
At baseline, the control and Prolibra groups were consum-
ing comparable amounts of carbohydrate, protein, fat and
calcium (Table 3). Table 4 shows the macronutrient
Table 2: Composition of Prolibra.
Component Daily Intake
Protein (g) 20
Leucine (g) 2.24
Isoleucine (g) 1.44
Valine (g) 1.26
Total BCAA 4.94
Lysine 1.91
Cysteine 0.50
Methionine 0.41
Tryptophan 0.44
Phenylalanine 0.64
Histidine 0.37
Threonine 1.59
Tyrosine 0.62
Lipid (g) 0.12
Carbohydrate (g) 0.83
Lactose (g) 0.27
Minerals
Calcium (mg) 482
Phosphorus (mg) 253
Sodium (mg) 213
Potassium (mg) 100
Magnesium (mg) 50
Zinc (ug) 60
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intake with and without the supplement during the diet-
ing phase of this trial. When the dietary records alone
were analyzed we did not find significant differences in
macronutrient intake during dieting between the Prolibra
and control groups in the completer or responder analysis
when the supplement was excluded from the analysis.
Including the supplement provided a significant shift in
carbohydrate to protein ratio.
Body composition
No baseline differences were found between groups for
any body composition parameters (Table 1). After 12
weeks there were significant differences (Table 5). Weight
loss was consistently higher in the Prolibra subjects and
DEXA analyses showed that the weight loss in the Prolibra
group was primarily the result of losing body fat. Prolibra
subjects lost significantly more body fat compared to con-
trol subjects in both the completer (2.81 kg vs. 1.62 kg P
= 0.03) and responder (3.63 kg vs. 2.11 kg, P = 0.01) anal-
ysis. The Prolibra subjects lost significantly less lean mus-
cle mass compared to control subjects in the responder
analysis (2.41 kg vs. 1.07 kg, P = 0.02); however the com-
pleter analysis did not show a significant difference
between Prolibra and control subjects (1.55 kg vs. 0.75 kg,
P = 0.11). Fat loss to lean loss ratio (kg fat loss/kg of lean
loss) for Prolibra subjects was higher compared to the
control in both the completer (3.75 vs. 1.05) and
responder (3.39 vs. 0.88) analysis.
Blood chemistry
Table 6 contains the changes in blood profiles during the
study for the completer analysis. Similar trends were
observed in the responder analysis. There was a significant
within group decrease of cholesterol for the treatment
group. There was also a significant decrease in blood urea
nitrogen in the control group. Tables 5, 6 summarize the
significant within group and between group differences.
Discussion
Supplementation with Prolibra during dieting increased
the loss of body fat and the retention of lean muscle mass
compared to supplementation with an isocaloric control
that had a lower calcium and lower protein content. Pro-
libra appears to preserve lean muscle and may partition
Table 3: Daily food intake at baseline (mean ± standard error)
Baseline food intake
Completers Responders
Control group Prolibra group Control group Prolibra group
Carbohydrate (g) 211 ± 10 222 ± 11 219 ± 12 219 ± 12
Protein (g) 74 ± 4 73 ± 3 82 ± 4 73 ± 4
Fat (g) 71 ± 5 75 ± 5 74 ± 5 72 ± 6
EtOH (calories) 50 ± 16 38 ± 16 30 ± 9 50 ± 21
Calcium (mg) 381 ± 36 372 ± 30 370 ± 39 359 ± 40
g protein/kg body weight* 0.76 0.74 0.82 0.74
Carbohydrate/Protein ratio 2.9 3.0 2.7 3.0
*Initial body weight was used for this calculation.
Table 4: Daily food intake during dieting (mean ± standard error).
Food intake during dieting*
Completers Responders
Control group Prolibra group Control group Prolibra group
Carbohydrate (g) 182 ± 9 178 ± 8 174 ± 13 178 ± 11
Protein (g) 58 ± 2 57 ± 3 56 ± 3 60 ± 5
Fat (g) 47 ± 3 49 ± 3 43 ± 4 47 ± 5
EtOH (calories) 20 ± 7 13 ± 5 11 ± 6 16 ± 6
Calcium (mg) 317 ± 29 275 ± 27 242 ± 26 287 ± 33
g protein/kg weight** 0.61 0.60 0.58 0.63
Carbohydrate/Protein ratio 3.1 3.1 3.1 3.0
With supplement
g protein/kg weight 0.61 0.81 0.58 0.84
Carbohydrate/Protein ratio 3.6 2.4 3.6 2.3
*The nutritional supplements were not included in the dietary calculations.
**Final body weight was used for this calculation.
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the weight loss predominantly towards fat at a lower pro-
tein dose, 20 grams per day. Being able to target body fat
while retaining lean muscle provides a healthy scenario
for weight loss and the potential to decrease body fat.
Layman et al. [5] compared diets with differing carbohy-
drate to protein ratios. Their control group consumed a
carbohydrate to protein diet of 3.5:1 with 0.8 grams/kg/
day protein intake compared to a treatment group that
consumed a 1.5:1 diet with 1.5 grams/kg/day protein.
These two groups were calorically restricted to approxi-
mately 1,700 cal/day. No significant difference in weight
lost was found between the two groups; the high protein
group showed a partitioning of the weight loss that pre-
served lean and targeted fat loss. In our study, with an
incremental intake of 20 grams protein per day in the Pro-
libra group (total intake 0.8 g/kg/day), we observed fat-
directed weight loss of 79% (fat loss/(lean loss + fat loss)
× 100) compared to 87% reported in the high protein
group of the Layman study with an intake of 1.5 g protein/
kg/day.
Conclusion
Subjects in both the control and treatment group lost a
significant amount of weight with a 500 calorie reduced
diet. Subjects taking Prolibra lost significantly more body
Table 5: Weight loss, fat loss and lean loss over 12 weeks (mean ± standard error).
Completers Responders
Control Prolibra Control Prolibra
Number of subjects 28 31 19 23
Weight loss (kg) 3.24 ± 0.47
#
3.82 ± 0.55
#
4.56 ± 0.41
#
5.20 ± 0.47
#
% Increase total body water 0.50 ± 0.59
NS
1.21 ± 0.51
#
1.00 ± 0.52
NS
1.40 ± 0.66
#
Decrease in REE (kCal) 76 ± 52
NS
40 ± 38
NS
147 ± 69
#
37 ± 60
NS
Centimeters lost (waist) 5.34 ± 0.97
#
6.22 ± 0.84
#
6.15 ± 1.20
#
7.42 ± 0.86
#
Centimeters lost (hip) 4.90 ± 0.84
#
4.20 ± 1.55
#
5.41 ± 1.04
#
4.47 ± 2.03
#
Fat mass lost (kg) 1.62 ± 0.33
#*
2.81 ± 0.38
#*
2.11 ± 0.44
#*
3.63 ± 0.40
#*
Lean mass lost (kg) 1.55 ± 0.39
#
0.75 ± 0.34
#
2.41 ± 0.44
#*
1.07 ± 0.37
#*
# statistically significant (P < 0.05) result within group.
* statistically significant (P < 0.05) result between group.
NS
Not significant
Table 6: Change in blood profiles during dieting based upon completers analysis (mean ± standard error).
Blood Chemistries Control Prolibra
Triglycerides (mg/dl) -7.5 ± 16 -16.9 ± 10
Cholesterol (mg/dl) -2.21 ± 4 -9.26 ± 4
#
High Density Lipoproteins (mg/dl) 0.93 ± 1 -1.06 ± 1
Low Density Lipoproteins (mg/dl) -0.32 ± 4 -5.43 ± 4
Blood Urea Nitrogen (mg/dl) -1.32 ± 0.5
#*
0.1 ± 0.6*
Creatine (mg/dl) 0 ± .02 0.01 ± .01
Albumin (g/dl) 0 ± 0.4 0.03 ± .03
Globulin (g/dl) -0.07 ± .05* 0.05 ± 0.5*
Alkaline Phosphatase (u/l) -0.96 ± 1.3 3.52 ± 2.6
Aspartate amino transferase (u/l) -0.64 ± 0.51 -0.13 ± 0.94
Alanine amino transferase (u/l) -1.64 ± 0.80
#
-0.94 ± 1.01
Hemoglobin (g/dl) -0.12 ± 0.18 0.15 ± 0.10
Immune Parameters (Thous/mm3) Control Treatment
White Blood Cells -0.77 ± 0.32 -0.52 ± 0.26
Platelet Count -16.54 ± 4.34
#
-13.13 ± 5.72
#
Absolute Neutrophils -0.42 ± 1.54 0.08 ± 1.19
Absolute Lymphocytes 0.12 ± 1.32 0.29 ± 0.94
Absolute Monocytes 0.19 ± 0.22 -0.13 ± 0.29
Absolute Eosinophils 0.01 ± 0.17 -0.27 ± 0.27
Absolute Basophils 0.12 ± 0.08 0.03 ± 0.05
# Significant difference (P < 0.05) within group (Time 0 versus Time 12 weeks)
* Signficant difference (P < 0.05) between group at 12 weeks
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Nutrition & Metabolism 2008, 5:8 http://www.nutritionandmetabolism.com/content/5/1/8
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fat and showed a greater preservation of lean muscle com-
pared to subjects consuming the control beverage.
Because subjects taking Prolibra lost 6.1% of their body
fat mass, and because a 5% reduction of body fat mass has
been shown to reduce the risk of obesity related disease
[3,30], the results have practical significance.
Competing interests
The study was funded by Glanbia Nutritionals Inc that
manufactures and sells Prolibra. Both LSW and EDB are
employees of Glanbia Nutritionals Inc.
Authors' contributions
All authors contributed equally to the design and develop-
ment of this clinical trial that was conducted at the Min-
nesota Applied Research Center by JLF and JLZ. MAK was
the independent statistician responsible for the statistical
analysis. LSW prepared the first draft of the manuscript.
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... Normal aging involves important changes in the body composition, including decreased muscle mass and increased fat mass [4]. With aging, the body's muscle mass steadily decreases by 1%-2% annually after the age of 50, and the resulting decrease in the basal metabolic rate induces body fat mass and weight gain [5,6]. Age-related changes contribute to age-related diseases such as cardiovascular events, diabetes mellitus, hypertension, and several types of cancer [7]. ...
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We all know that we shouldn't put too much salt on our food because it might cause our blood pressure to go up. In his Perspective, McCarron argues that the scientific evidence actually tells us something different: Salt has little effect on blood pressure, and the most effective diet-induced changes in blood pressure can be achieved with a menu low in fat but high in calcium, fruits, and vegetables.
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Objectives: To test the hypothesis that unintentional weight loss increases the rate of bone loss and risk of hip fracture more than intentional weight loss. Design: Prospective cohort study. Setting: Four communities within the United States. Participants: Six thousand seven hundred eighty-five elderly white women with measurement of weight change and assessment of intention to lose weight. Measurements: Weight change between baseline and fourth examinations (average 5.7 years between examinations) and assessment of intention to lose weight. Weight loss was defined as a decrease of 5% or more from baseline weight, stable weight was defined as less than a 5% change from baseline weight, and weight gain was defined as an increase of 5% or more from baseline weight. Rate of change in bone mineral density at the hip between fourth and sixth examinations (average 4.4 years between examinations) was measured using dual-energy x-ray absorptiometry. Incident hip fractures occurring after the fourth examination until June 1, 2001 (average follow-up 6.6 years) was confirmed using radiographic reports. Results: The adjusted average rate of decline in total hipbone density steadily increased from −0.52% per year in women with weight gain to −0.68% per year in women with stable weight to −0.92% per year in women with weight loss (P-value for trend <.001). Higher rates of hip-bone loss were observed in women with weight loss irrespective of body mass index (BMI) or intention to lose weight. During follow-up of an average 6.6 years after the fourth examination, 400 (6%) of the cohort suffered a first hip fracture. Women with weight loss had 1.8 times the risk (95% confidence interval (CI)=1.43–2.24) of subsequent hip fracture as those with stable or increasing weight. The association between weight loss and increased risk of hip fracture was consistent across categories of BMI and intention to lose weight. Even voluntary weight loss in overweight women with a BMI of 25.9 kg/m2 (median) or greater increased the risk of hip fracture (multivariate hazard ratio=2.48, 95% CI=1.33–4.62). Conclusion: Older women who experience weight loss in later years have increased rates of hip-bone loss and a two-fold greater risk of subsequent hip fracture, irrespective of current weight or intention to lose weight. These findings indicate that even voluntary weight loss in overweight elderly women increases hip fracture risk.
Article
It is unclear whether low-carbohydrate, high-protein, weight-loss diets benefit body mass and composition beyond energy restriction alone. The objective was to use meta-regression to determine the effects of variations in protein and carbohydrate intakes on body mass and composition during energy restriction. English-language studies with a dietary intervention of > or =4200 kJ/d (1000 kcal/d), with a duration of > or =4 wk, and conducted in subjects aged > or =19 y were considered eligible for inclusion. A self-reported intake in conjunction with a biological marker of macronutrient intake was required as a minimum level of dietary control. A total of 87 studies comprising 165 intervention groups met the inclusion criteria. After control for energy intake, diets consisting of < or =35-41.4% energy from carbohydrate were associated with a 1.74 kg greater loss of body mass, a 0.69 kg greater loss of fat-free mass, a 1.29% greater loss in percentage body fat, and a 2.05 kg greater loss of fat mass than were diets with a higher percentage of energy from carbohydrate. In studies that were conducted for >12 wk, these differences increased to 6.56 kg, 1.74 kg, 3.55%, and 5.57 kg, respectively. Protein intakes of >1.05 g/kg were associated with 0.60 kg additional fat-free mass retention compared with diets with protein intakes < or =1.05 g/kg. In studies conducted for >12 wk, this difference increased to 1.21 kg. No significant effects of protein intake on loss of either body mass or fat mass were observed. Low-carbohydrate, high-protein diets favorably affect body mass and composition independent of energy intake, which in part supports the proposed metabolic advantage of these diets.