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Original Paper
Nutrition&
Metabolism
KeyWords
Diet . Exercise .Weight loss ' Energy balance '
Body composition . Lipid profile
Abstract
Background; This study was designed to compare the ef-
fects of 2 different but isocaloric fat reduction programs
with the same amount of energy deficit - diet alone or diet
combined with aerobic training - on body composition, lip-
id profile and cardiorespiratory fitness in non- or moderate-
ly obese women. Methods: Twenty non- or moderately
obese (BMl 24.32 + 3.11)females (21.2 + 6.6 years) were test-
ed at the beginning and after an S-week period of a mild
hypocaloric diet for the following parameters: (1) body mass
and body fau (2) total cholesterol, HDL-C, LDL-C and triglyc-
erides; (3) lactate (millimol/liter) during submaximal ex-
ertion (100 W); (4) heart rate during submaximal exertion
(100 W), and (5) maximum exercise performance (watt). Sub-
jects were randomly divided into either a diet alone (D,
-2,095 + 659 kJ/day) or a diet (-1,420 + 1,084 d/day)
plus exercise (DE, three 60-min sessions per week at 600/o of
VO2max or -5,866 kJlweek) group. Results: Body mass and
bodyfat decreased significantly in D (-1.95 + 1.13 kg or -1.47
+ 0.87o/o) p < 0.05) and DE (-2.21 + 1.28 kg or -1.59 + 0.87o/o;
Received: November 7, 2006
Accepted: April 20, 2007
Published online: November 20, 2007
p < 0.05), but there was no significant difference observed
between the groups. Statistical analysis revealed no signifi-
cant changes of total cholesterol, HDL-C, LDL-C, triglycerides
and heart rate during submaximal exertion (100 W). Lactic
acid accumulation during submaximal exertion (100 W) de-
creased significantly (-O.g + 1.4 mmol/|, p < 0.05) in DE and
increased significantly (+0.+ + 0.5 mmol/|, p < 0.05) in D.
Maximum exercise performance improved significantly
(+lZ.Z + 8.8 W p < 0.05) in DE and did not change signifi-
cantly in D. Conclusions.'This study showed that indepen-
dently of the method for weight loss, the negative energy
balance alone is responsible for weight reduction.
Copyright o 2007 5. Karger AG, Basel
Introduction
Obesity is the result of excess energy intake compared
to energy expenditure. To lose weight, a negative energy
balance must be evoked [1]. Dietary restriction and exer-
cise are useful methods to create a negative energy bal-
ance. However, the existent literature appears to provide
little evidence that exercise alone is a potent strategy for
loss of body mass (BM). The lack of efficacy for exercise
to promote BM loss may be in part due to the relatively
Ann Nutr Metab 2007;51:428-432
DOI: 1 0.1 1 59/0001 1'l 162
Fat Loss Depends on Energy
Deficit Only, lndependently of the
Method for Weight Loss
B. Strasseru A. Spreitzerb P. Habera
aDepartment of lnternal Medicine lV Division of Sports Medicine, Medical University Vienna, and
blnstitute of Nutritional Sciences, University of Vienna, Vienna, Austria
KARGER
Fil +41 61 306 12 34
E-Mai1 karger@kargerch
rmw.kargercom
O 2007 S. Karger AG, Basel
0250 - 6807 I 07 I 0515 0428$23.s0/0
Accessible online at:
www.karger.com/anm
Dr. Barbara Strasser
Zentrum für medizinische Trainingstherapie und Trainingsberatung
Roetzergasse 41l1, AT 1170 Vienna (Austria)
Tel. +43 t 485 8164 11, Fax +43 1 485 8164 13
E-Mail barbara.strasser@trainingstherapie.at
low amount that has been used in exercise studies. Ross
et al. showed that the energy expenditure ofexercise has
to be between 2,000 and 3,000 ki per day to provide a BM
loss of approximately 6 kg in women l2l and 8 kg in men
[3] within 12 weeks. Similarly, in findings by Donnelly et
al. [4], with increased levels of energy expenditure of ex-
ercise, loss of BM was shown in men but to a lesser extent
in women. Fogelholm [5] reviewed the effects of walking
(150-225 min/week) on BM reduction in obese partici-
pants with or without a low-energy diet (5,000 -7,000k|l
day). The mean BM reduction during 3-6 months when
walking was added to diet was numerically (by 0.3-2.1
kg) but not significantly better than the diet-only group.
Utter et al. [6] measured the influence of diet (5,000-
5,500 kl/dar, exercise (225 minlweek at 78.5 + 0.5o/o
maximum heart rate) or both on body composition and
cardiorespiratory fitness in obese women. The results in-
dicated that moderate aerobic training during a l2-week
v period had no discernible effects on body composition
but improved cardiorespiratory fitness in dieting obese
women. Serum cholesterol and triacylglycerol improved
in both diet and in exercise plus diet groups after 12 weeks
of intervention and was most strongly related to BM loss
[7]. Himeno et al. [8] evaluated the effects of exercise and
a mild hypocaloric diet on cardiovascular risk factors in
obese subjects. After 12 weeks, a combination of aerobic
exercise and a mild hypocaloric diet significantly con-
tributed not only to the loss of BM but also to the im-
provement of dyslipidemia and exercise performance, but
either hypocaloric diet or mild exercise independently
had less effects.
Thus, there is strong evidence that hypocaloric diets
and physical activity can induce loss of BM in obese pa-
tients. Nutrition therapy and increased physical activity
improve obesity-associated risk factors and can prevent
. or delay comorbidities [9].
\-/ The above-mentioned studies suggest that exercise ac-
tivity alone reduces BM only slightly and that only the
combination of both, diet and training, leads to signifi-
cant BM reduction. Moreover, exercise activity reduces
the diet-induced loss of fat-free mass and favors BM re-
duction through an increased metabolic rate [10]. Unfor-
tunately, most of the exercise studies for BM reduction
did not measure the total caloric deficit and its correla-
tion with the loss of BM.
The new aspect of our study is that fat loss is exclu-
sively determined by the amount of the energy deficit in-
dependently of the method achieving the negative energy
balance. Therefore, we compared the effects of a negative
balance by 1,680 k| per day, once obtained by diet alone
and once composed of diet and aerobic training, on body
composition, blood lipid profile and cardiorespiratory
fitness in non- and moderately obese women.
Methods
Study Population
We recruited 20 non- or moderately obese (BMl 24.32 + 3.11)
females (22.5 + 6.6 years) through advertisements from the sur-
rounding community. Subjects were randomly divided into either
a diet alone (D, -1,680 kl/day) or a diet (-840 kl/da, plus exercise
(DE, three 60-min sessions per week at 60%o of VO2max or -840
kl/da, group. Measurements of energy intake, body composition,
serum lipids and cardiorespiratory fitness were conducted in all
subjects before and after an 8-week exercise and/or energyrestric-
tion intervention period.
Dietary Program
Prior to the study, all subjects kept a 3-day food record. Sub-
jects ofD were placed on a 1,680- and subjects ofDE on an 840-kf
caloric deficit per day. Subjects were instructed on portion sizes
and how to record dietary intake using a daily dietary protocol.
Compliance with the diet was measured in all subjects byrandom,
weekly, 24-how dietary recalls. Nutrient intake from the 3-day
food records and 24-hour dietary recalls was assessed using a
computerized dietary analysis system (WVG software, Prodi@,
version 4.5 LE compact+). The dietary menu was based on 25 en-
ergy percent fat, 55-60 energy percent carbohydrates and 15-20
energy percent proteins.
Training Program
To reach an isocaloric energy reduction, subjects in the DE
group were required to walk or run 3 times a week under supervi-
sion of a trainer, 60 min per session (in dependence on physical
fitness), at600/o of YO2max, for 8 weeks. Exercise heart rates were
measured with chest heart rate monitors (Polar@). The net energy
expenditure during exercise was derived by using the following
formula [11]: 4.19 kf per kg BM per km.
Fitness and Status of Blood Lipids
Body Mass Index.Eachparticipant had her bodyweight (Tani-
ta@ BWB-620, to the nearest 0.1 kg) and height (to the nearest 0.1
cm) recorded while wearing light indoor clothes but no shoes. BM
was tested before and after the study, with weekly weigh-ins con-
ducted for all subjects during the B-week intervention.
Body Fat. During the week prior to and at the end of the 8-
week study, all subjects were tested for body fat (in percent of
body weight) using the bioelectrical impedance analysis method
(Omron@ BF 302).
Serum Lipids. Venous blood was drawn after overnight fast-
ing. Serum total cholesterol, high-density lipoprotein cholesterol
(HDL-C), low-density lipoprotein cholesterol (LDL-C) and tri-
glycerides were measured before and after the studyby the clinical
laboratory of the Medical University Vienna. Samples were ana-
lyzed on the day they were collected.
Maximal Aerobic Power. Prior to and at the end of the 8-
week study, all subjects underwent a cycling test on an electri-
cally braked cycle ergometer (Ergoline@ Ergometrics 900) to the
Fat Loss Depends Only on Energy Deficit Ann Nutr Metab 2007;51:428-432 429
Table '1. Subject characteristics and treatment regimens at base-
line (mean + SD)
Characteristics and regimens Diet plus
exercise
Age, years 25.8+ 6.9 ZB.B+ 6.4 n.s.
Body mass, kg 67.2+ 9.4 68.6 + 6.6 n.s.
Body mass index 23.9 + 3.8 24.7 + 2.4 n.s.
Body fat, 7o 24.6 + 6.9 27.1 + 6.0 n.s.
Energyintake,kJlday 9,704+ t,920 9,574+ I,535 n.s.
Cardiorespiratory fitness, W 161.8 + 26.1 165.9 + 32.t n.s.
Table 2. Effect ofexercise training and energy restriction on body
composition and cardiorespiratory endurance over 8 weeks in 20
non- or moderately obese females (mean + SD)
Table 3. Effect ofexercise training and energy restriction on se-
rum lipids over 8 weeks in 20 non- or moderately obese females
(mean + SD)
Diet
(n = 10) Diet plus
exercise
(n = 10)
p
value
Cholesterol, mg/dI
Before study
After study
HDL-C, mg/dl
Before study
After study
LDL-C, mg/dl
Before study
After study
Triglycerides, mg/di
Before study
After study
173.7 + 28.5 208.5 + 40.4 >0.05
1.79.9 + 24.5 208.4+ 35.9
64.2+ t3.3
61.5 + 8.8
89.9 + 28.3
93.3 + 25.3
97.7 + 40.5
104.9 + 54.7
65.4+ 77.8 >0.05
66.5 + t2.3
t24.4+ 34.2 >0.05
t23.5 + 33.8
93.9 + 30.4 >0.05
92.6 + 26.9
Heart rate (l/min) submaximal exertion, 100 W
p < 0.05, statistically significant.
Results
Statistical analysis was performed using the statistical
computer software SPSS (Statistical Package for Social
Sciences, SPSS Inc., Chicago, I11., USA;version 11.0). The
arithmetic mean and the standard deviation were calcu-
lated for all data. p values (0.05 were considered statisti-
cally significant. In order to exclude significant differ-
ences between the groups prior to the study, the indepen-
dent-sample t test was used. To document changes of
several variables between the first and the second test, the
paired t test and the Shapiro-Wilk test were applied. To
compare the 2 groups at the end of the study, the 2-sample
t test was used.
At study entry, D and DE groups had similar profiles
for all parameters (table 1). Prior to the study, 3-day food
records indicated a caloric intake of 9,704 + 1,920 and
9,574 + 1,535 kf/day for the D and DE group, respective-
ly. Subjects of D decreased the energy intake on a2,095
+ 638 k|, subjects of DE on a 1,420 + 1,084 kl caloric
deficit per day, respectively. Together with the energy ex-
penditure by exercise, DE had a daily energy deficit of
1,982 + 595 kllday. This was not significantly different
from D.
Body composition and cardiorespiratory endurance
are summarized in table 2. BM and body fat decreased
significantly (-Z.t + 1.2 kg or -1.53 + 0.87o/o; p < 0.05)
Diet
(n = l0) Diet pius
exercise
(n = 10)
Body mass, kg
Before study
After study
Body mass index
Before study
After study
Body fat,o/o
Before study
After study
Cardiorespiratory fi tness, Wmax
Before study
After study
Before studv
After studv
Before study
After study
Lactate (mmol/l) submaximal exertion, 100 W
67.2+ 9.4
65.2+ B.7x
23.9 + 3.8
23.3 + 3.6
24.6+ 6.9
23.t+ 6.8
76t.8 + 26.t
754.5 + 24.6
t49.3+ 14.5
150.5 + 13.5
3.9 + 1.1
4.3+ 1.2x
68.6+ 6.6
66.4+ 6.6x
24.7 + 2.4
23.9 + 2.4
27.1 + 6.0
25.5+ 6.2*
165.9 + 32.t
178.1 + 37.6x
t45.7 + t6.5
t41.8+ 20.4
4.0+ t.7
3.2 + 0.gx
x p < 0.05, statistically significant.
point of exhaustion. Heart rate was continuously monitored via
an electrocardiogram, with blood pressure measured in the final
minute of each work level. Exercise started with a work load of
50 W and was increased stepwise by 25 W every 2 min until ex-
haustion. The following parameters were determined: maximal
power (in watt), maximal heart rate, heart rate and lactate during
submaximal exertion (100 W). Capillary blood was drawn from
the earlobe and analyzed for lactate (Eppendorf@ E SAT 6661 Lac-
tat) at rest, in the final minute of each work level and 3 min after
exhaustion.
430 Ann Nutr Metab 2007;51:428-432 Strasser /Spreitzer I }Iab er
in both groups (D+DE), but there was no significant dif-
ference observed between the groups. Subjects in D and
DE lost 1.95 + 1.13 and 2.23 + 1.29 kg BM and 1.47 +
0.87 and 1.59 + 0.87o/o body fat, respectively, during
the study. Lactic acid accumulation during submaxi-
mal exertion (100 W) decreased significantly (-0.8 + 1.4
mmol/I, p < 0.05) in DE and increased significantly (+0.4
+ 0.5 mmol ll,p <0.05) in D. Maximum exercise perfor-
mance improved significantly (+12.2 + 8.8 W p < 0.05)
in DE and did not change significantly in D. We found no
significant changes of heart rate during submaximal ex-
ertion (100 W). Table 3 summarizes the serum lipid data.
Statistical analysis revealed no significant changes ofto-
tal cholesterol, HDL-C, LDL-C and triglycerides for both
groups.
Discussion
In this randomized, controlled 8-week study of a group
of 20 non- or moderately obese women, energy restriction
alone or in combination with aerobic training signifi-
cantly lowered BM and percent body fat. Serum lipids and
heart rate during submaximal exertion did not change in
either group, while lactic acid accumulation during sub-
maximal exertion decreased and maximum exercise tol-
erance improved significantly in the diet plus exercise
group.
This study showed that independently of the method
for BM loss, the negative energybalance alone is respon-
sible for BM reduction. The mean loss of BM of 1.95 +
1.13 kg in the diet group was nearly identical to 2.23 +
1.29 kg in the diet plus exercise group. Further, we did not
find any significant difference in fat loss between the
groups (1.+Z + 0.87 and 1.59 + 0.87o/o for the diet and
diet plus exercise group, respectively).
Therefore, to lose body fat, more calories have to be
expended than consumed at the end of the day. However,
most of the exercise studies suggest that exercise activity
alone has only a minor influence on fat reduction and
that mainly the combination of both, diet and exercise
training, leads to significant reduction of BM. Unfortu-
nately, the classic explanation for the secondary role of
exercise is that exercise alone cannot generate enough en-
ergy expenditure to create a negative energy balance to
the extent possible with energy restriction. Ross et al. [2]
stated that the energy expenditure of exercise has to be
between 2,000 and 3,000 kl per day to provide a BM loss
of approximately 6 kg for women within 12 weeks. This
is true but it is also true that a negative energy balance of
2,500-3,350kllday always causes a fat loss of 6-8 kg with-
in 3 months [84 days x 2,500 klldayl39,900 k/kg fat =
5.3 kg fat loss - this is comparable with a BM loss of 6 kgl.
These studies for BM reduction did not measure the total
caloric deficit and its correlation with the loss of BM. In
fact, the amount of fat reduction simply depends on ca-
loric deficit, independently of the method for BM loss.
Numerous studies and reviews have concluded that
moderate exercise training has little effect on total cho-
lesterol or LDL-C unless combined with weight loss or
change in dietary quality [12].In our study, a mild hypo-
caloric diet with or without aerobic training was insuf-
ficient to stimulate changes in lipid profile. The reason
could be explained by the young study population (27.3
+ 6.6 years) with nearly normal B}iII (24.32 + 3.11) and
blood lipid profile.
The effectiveness of aerobic training in the diet plus
exercise group was shown by a12.2 + 8.8 watt improve-
ment in cardiorespiratory fitness and a 0.8 + 1.4
mmol/l reduction of lactic acid accumulation during sub-
maximal exertion, while in the diet-only group cardiore-
spiratory fitness decreased by 7.3 + 12.9 W and lactic
acid accumulation during submaximal exertion increased
significantly by 0.4 + 0.5 mmol/I.
Conclusion
This study showed that reduction of body fat simply
depends on energy deficit, and that independently ofthe
method for body fat loss solely a negative energybalance
is responsible for the amount of body fat reduction. Diet
combined with aerobic training has the benefit of a gain
in physical fitness in addition to fat loss.
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