Exercise training as an adjunct to orlistat therapy reduces oxidative stress in obese subjects.

Abstract

The anti-obesity drug orlistat promotes weight loss and improves obesity-related risk factors, but its effect on oxidative stress is not clear yet. Orlistat reduces dietary fat absorption, which may have effects on fat soluble vitamins especially the antioxidant vitamins A and E. The aim of this study was to determine and compare the effects of weight loss achieved by orlistat therapy and a combination of orlistat with aerobic exercise training on lipid peroxidation and antioxidative defense in obese subjects. Total of 24 obese subjects were randomly assigned to receive 12-week treatment with hypocaloric diet-orlistat (120 mg three times daily) (DO group) or diet-orlistat-exercise (DOE group). Serum levels of malondialdehyde (MDA), a marker for lipid peroxidation, and vitamins A and E were measured by high performance liquid chromatography at baseline and at the end of the treatment. Body weight and fat mass were significantly reduced in the two groups (p < 0.001). In the DO group, the MDA levels remained unchanged (p = 0.59), while vitamins A (p < 0.01) and E (p < 0.001) were significantly decreased. In contrast, the subjects treated with DOE exhibited marked decreases in MDA (p = 0.002) and a small but significant decrease in vitamins A (p = 0.003) and E (p = 0.003). Thus, orlistat therapy alone caused a significant reduction in antioxidative capacity without affecting oxidative stress, whereas orlistat in combination with exercise training provided a significant decrease in MDA levels. The beneficial effect of aerobic exercise as an adjunct to the orlistat therapy is of importance with regard to the obesity-associated risk factors.

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Orlistat Therapy and Oxidative Stress313
313
Tohoku J. Exp. Med., 2005, 206, 313-318
Received February 14, 2005; revision accepted for publication May 23, 2005.
Correspondence: Dr. Oguz Ozcelik, Fırat University, Faculty of Medicine (Tip Fak), Department of Physiolo-
gy, Elazig, Turkey.
e-mail: oozcelik@excite.com or oozcelik@firat.edu.tr
Exercise Training as an Adjunct to Orlistat Therapy
Reduces Oxidative Stress in Obese Subjects
OGUZ OZCELIK, YUSUF OZKAN,1 FIKRET KARATAS2 and HALUK KELESTIMUR
Department of Physiology, 1Department of Endocrinology and Metabolic
Disease, Firat University Faculty of Medicine, Elazig, and
2Firat University Faculty of Chemistry, Elazig, Turkey
OZCELIK, O., OZKAN, Y., KARATAS, F. and KELESTIMUR, H. Exercise Training as an
Adjunct to Orlistat Therapy Reduces Oxidative Stress in Obese Subjects. Tohoku J. Exp.
Med., 2005, 206 (4), 313-318 ─ ─ The anti-obesity drug orlistat promotes weight loss and
improves obesity-related risk factors, but its effect on oxidative stress is not clear yet.
Orlistat reduces dietary fat absorption, which may have effects on fat soluble vitamins
especially the antioxidant vitamins A and E. The aim of this study was to determine and
compare the effects of weight loss achieved by orlistat therapy and a combination of
orlistat with aerobic exercise training on lipid peroxidation and antioxidative defense in
obese subjects. Total of 24 obese subjects were randomly assigned to receive 12-week
treatment with hypocaloric diet-orlistat (120 mg three times daily) (DO group) or diet-
orlistat-exercise (DOE group). Serum levels of malondialdehyde (MDA), a marker for
lipid peroxidation, and vitamins A and E were measured by high performance liquid
chromatography at baseline and at the end of the treatment. Body weight and fat mass
were significantly reduced in the two groups (p < 0.001). In the DO group, the MDA
levels remained unchanged (p = 0.59), while vitamins A (p < 0.01) and E (p < 0.001) were
significantly decreased. In contrast, the subjects treated with DOE exhibited marked
decreases in MDA (p = 0.002) and a small but significant decrease in vitamins A (p = 0.003)
and E (p = 0.003). Thus, orlistat therapy alone caused a significant reduction in antioxida-
tive capacity without affecting oxidative stress, whereas orlistat in combination with
exercise training provided a significant decrease in MDA levels. The beneficial effect of
aerobic exercise as an adjunct to the orlistat therapy is of importance with regard to the
obesity-associated risk factors. ──── obesity; body mass index; MDA; orlistat; exercise
© 2005 Tohoku University Medical Press
Obesity increases risk for many common
diseases, including type 2 diabetes mellitus, sys-
temic hypertension, dyslipidemia and coronary
artery diseases (Calle et al. 1999). Although the
etiology of obesity is complicated and not well
understood, various factors, including interactions
of genetic, metabolic, nutritional, cultural and
psychosocial are thought to be the major determi-
nants in obesity etiology. Current strategies for
preventing and treating obesity involve diet, exer-
cise, pharmacotherapy and their combinations
(Bray and Greenway 1999). The commonly ac-
cepted primary target for the obesity management
program is based on the achievement of 5-10%

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O. Ozcelik et al.314
weight loss from the initial body weight, which is
often sufficient to reduce obesity related risk fac-
tors (Lindgarde 2000; Mertens and Van Gaal
2000).
Orlistat (tetrahydrolipstatin, XenicalTM) is a
widely used peripherally acting anti-obesity drug.
It promotes weight loss by reducing 30% of fat
absorption from the intestine through a gastric
and pancreatic lipases inactivation (Curran and
Scott 2004). The specific effects of orlistat on
body weight and blood lipid parameters have been
shown in previous studies (Van Gaal et al. 1998;
Lindgarde 2000). However, the oxidative stress,
which is a normal product of body processes, is
another important point to be considered in obesi-
ty management. It has been reported that oxida-
tive stress is markedly high in obese subjects
compared to normal weight subjects (Keaney et
al. 2003; Mutlu-Turkoglu et al. 2003). Yet an in-
creased oxidative stress has been shown to be as-
sociated with many chronic progressive diseases
(Cerutti 1994; Singal et al. 2001).
Effect of weight loss induced by orlistat
therapy on oxidative stress and antioxidant system
has not been well documented yet. Since orlistat
reduces fat absorption from intestinal system, it
may have effects on fat soluble vitamins including
the antioxidant vitamins A and E (Melia et al.
1996; McDuffie et al. 2002). Therefore, the im-
portant issue that needs to be addressed in obesity
management is whether oxidative stress is influ-
enced by the weight loss induced by orlistat to re-
duce mortality and morbidity.
In the present study, we aimed to determine
and compare the effects of weight loss achieved
by orlistat therapy alone and a combination of or-
listat therapy with aerobic exercise training pro-
gram on lipid peroxidation and antioxidative de-
fence in obese subjects.
METHODS
The protocol of this study, designed according to
Helsinki Declaration on human subjects, was approved
by Institutional Ethics Committee. Informed written
consents were obtained from each patient at the start of
the study. The study was carried out on an out-patient
basis with subjects returning to our center at weekly in-
tervals to be weighed.
This study was conducted over a 12-week period by
utilizing the weight loss program with orlistat alone or in
combination with aerobic exercise training. Following a
complete medical history, physical examination and ba-
sic laboratory studies conducted at the beginning of the
study, only those subjects found to be free of severe
medical problems were chosen for participation. A total
of 24 obese patients (22 females and 2 males) who were
treated for obesity at the Obesity Clinic, University of
Firat Hospital, participated in the study. Patients with
cortisol, thyroid, or insulin hormonal dysfunction, car-
diovascular diseases, and those taking any medications
known to affect body composition were excluded from
the study.
During the 12-week study period, the patients were
maintained on a nutritionally balanced mildly hypocalo-
ric diet (1,200-1,600 kcal/day). The prescribed diet con-
tained approximately 30% of calories from fat, 50% from
carbohydrate, 20% from protein. The patients received
dietary advice from a qualified dietitian. No vitamins
were provided, and patients were specifically asked not
to take any vitamin preparations, especially vitamins A, C,
and E and any antioxidant therapy.
The patients were randomly divided into two groups
(eleven females and a male patient for each group). One
group (DO group 40.0 ± 3.1 yr, and 159.5 ± 1.5 cm) re-
ceived orlistat 120-mg capsule tree times per day (120
mg prior to each meal), the dosage that has been shown
to be the most effective (Van Gaal et al. 1998). The sub-
jects in DO group were not given any instruction regard-
ing exercise. The other group (DOE group 37.3 ± 2.4 yr
and 159.0 ± 3.0 cm) performed a regular exercise train-
ing in addition to orlistat therapy. Each patient in DOE
group performed an incremental ramp test using an elec-
tromagnetically braked cycle ergometer (LODE,
Groningen, The Netherlands) to determine aerobic to an-
aerobic metabolic transition point (i.e., the anaerobic
threshold). The training work rate was set to the anaero-
bic threshold and performed three times per week, over a
12-week period. Each training session lasted for approx-
imately 45 min. Heart rate was monitored electrocar-
diograpically throughout the test.
Body composition was assessed using leg-to-leg
bioelectrical impedance method (Body Fat Analyser,
TBF 300 M, Tanita, Tokyo). The validity of this method
in the measurement of body composition in obese pa-
tients has been documented (Utter et al. 1999).
Blood samples were drawn at study entry and at the

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Orlistat Therapy and Oxidative Stress315
end of the 12-week therapy period. After an overnight
fasting, venous blood sample was obtained from forearm
in resting condition between 08:00 to 09:00 always ap-
proximately at the same time in the morning. The sam-
ples were separated by centrifugation and stored at
–70°C until analyzed for malondialdehyde (MDA), and
vitamins A and E.
The quantification was performed according to the
method of Miller et al. (1984) utilizing High Performance
Liquid Chromatography (HPLC). Separations were ac-
complished at room temperature with a Cecil liquid chro-
matography system (Series 1100) consisting a sample in-
jection valve (Cotati 7125) with a 20 μl sample loop, an
ultra-violet (UV) spectrophotometric detector (Cecil
68174), 326 and 296 nm for vitamins A and E, respec-
tively. Integrator (Hewlett Packard 3395) and a
Techsphere Octadecyl Silane-2 packed (5 μm particle
and 80Å pore size) column (250 × 4.6 Inner diameter)
with a methanol: acetonitril: chloroform (47: 42: 11,
volume/volume) as a mobile phase at 1.0 ml/min flow
rate.
The extraction of MDA was performed according to
Cerhata et al. (1994). The supernatant was filtered and
the free MDA level was determined by the method of
Karatas et al. (2002). The Tecopak C18 HPLC reversed-
phase column (10 μm particle size and 250 × 3.9 ID) was
used for the detection of MDA levels. The MDA level
was determined with mobil phase 30 mM potassium di-
hydrogen phosphate buffer, pH = 4 with phosphoric acid
and methanol (65%-35% volume/volume) at 1.5 ml/min
flow rate.
Data are presented as mean ± S.E.M. Mann
Whitney’s U-test was used to evaluate the statistical sig-
nificance on differences between the groups. In addition,
Wilcoxon Rank Test was used to evaluate the data in
same group for the basal and 12-week values. The statis-
tical differences were considered significant at p < 0.05.
RESULTS
The effects of the 12-week weight loss pro-
tocols, orlistat alone and its combination with ex-
ercise training, on body weight and fat mass are
given in Table 1. Total body weight loss was sig-
nificant in both groups: 8.5% in DO (p < 0.001)
TABLE 2. Serum levels of malondialdehyde (MDA) and vitamins A and E at baseline and at the end of the
12-week treatment with diet-orlistat (DO) and diet-oristat-exercise (DOE)
DO (n = 12)DOE (n = 12)
Baseline 12 weeks % change (p) Baseline12 weeks % change (p)
MDA
(μg/ml)
1.73 ± 0.1 1.67 ± 0.1NS
-3.4
p = 0.59
1.79 ± 0.08 1.20 ± 0.08*
-33.3
p = 0.002
Vit A
(μg/ml)
0.67 ± 0.090.37 ± 0.04-44.7
p < 0.001
0.63 ± 0.080.43 ± 0.05*
-31.7
p = 0.003
Vit E
(μg/ml)
6.13 ± 0.9 2.60 ± 0.2-57.6
p < 0.001
5.38 ± 0.53.83 ± 0.4*
-28.8
p = 0.003
* Statistically significant differences between the two groups.
NS, not significant.
TABLE 1. Body mass index (BMI), body weight (BW) and fat mass (FM) at baseline and at the end of
the 12-week treatment with diet-orlistat (DO) and diet-orlistat-exercise (DOE)
DO (n = 12)DOE (n = 12)
Baseline12 weeks Baseline12 weeks
BMI (kg/m2)
BW (kg)
FM (kg)
37.9 ± 1.2
96.9 ± 4.3
42.2 ± 2.9
34.7 ± 1.1*
88.6 ± 4.1*
36.6 ± 2.7*
39.1 ± 1.3
98.1 ± 4.5
42.7 ± 2.2
35.0 ± 1.2*
88.0 ± 4.2*
34.6 ± 2.2*
* Statistically significant compared to baseline (p < 0.001).

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O. Ozcelik et al.316
and 10.2% (p < 0.001) in DOE (Table 1). In addi-
tion, there was a marked decrease in fat mass in
both groups: 13.2% (p < 0.001) in the DO group
and 18.9% (p < 0.001) in DOE group (Table 1).
After the 12-week treatment, serum levels of
MDA were decreased markedly (33.3%) com-
pared with its baseline level in DOE group (p =
0.002). In contrast, there was no significant de-
crease (3.4%) in MDA levels in DO group (p =
0.59) (Table 2). Thus, the decrease in serum
MDA levels was significantly different between
the two groups (p = 0.01).
On the other hand, serum levels of vitamins
A and E were decreased in DO group (44.7%, p <
0.001 and 57.6%, p < 0.001, respectively). There
was a small but significant decrease in vitamin A
(31.7%, p = 0.003) and E levels (28.8%, p = 0.003)
in DOE group (Table 2). The decrease in vitamin
A (p = 0.04) and E (p = 0.04) levels was signifi-
cantly different between the two groups.
DISCUSSION
Although much research has been conducted
to investigate obesity and lipid peroxidation rela-
tionships, to our knowledge there are no satisfac-
tory results concerning the effects of weight loss
induced by orlistat therapy on lipid peroxidation
in obese patients. The effective and successful
treatment of obesity has to be one of the most dif-
ficult and complex task to challenge in clinical
medicine. Reduction of body weight, preventing
further weight gain and maintaining a lower body
weight over the long term are the general goals of
obesity management (Glazer 2001).
Orlistat in conjunction with diet has been
proven effective and safe in long-term of obesity
management (Lindgarde 2000; Mertens and Van
Gaal 2000). In the present study, orlistat therapy
combined with a dietary prescription helped pa-
tients to loss 8.5% of body weight and 13.2% of
fat mass, which are comparable with report of
previous short-term studies (Van Gaal et al. 1998;
Aydin et al. 2004). One may expect that the
achieved amount of weight loss during study peri-
od is in medically accepted optimal ranges and is
often sufficient to reduce obesity related risk fac-
tors (Lindgarde 2000; Mertens and Van Gaal
2000). Despite proven success in providing
weight loss, most of the current obesity manage-
ment protocols have not been evaluated with re-
spect to oxidative stress and lipid peroxidation,
which are secondary but significant end points. In
the present study, the weight loss induced by a
short-term orlistat therapy combined with energy
restricted diet did not have a significant effect on
MDA, which is one of the most frequently used
indicators of lipid peroxidation (Nielsen et al.
1997) (Table 2). This result is in contrary to the
finding of Yesilbursa et al. (2005) who observed
marked decreases in MDA in association with orl-
istat induced weight loss.
The high level of oxidative stress associated
with increased lipid peroxidation may be one of
the reasons why those who are overweight are at
greater risk for developing heart diseases (Rumley
et al. 2004). Considering abnormally high lipid
peroxidation and its damage to the body cells,
obesity management, providing reduction in
MDA level, serves a significant advantage in
obese patients. Decreases in lipid peroxidation
following weight loss induced by dietary restric-
tion in obese patients over a short period has been
reported (Dandona et al. 2002). The present study
provides data showing that weight loss induced
by a short-term orlistat therapy may not provide
significant beneficial effects on oxidative stress
and even impair the expected beneficial effect of
concurrently prescribed diet restriction. Orlistat
may reduce the absorption of fat soluble vitamins
including vitamins A and E, which contributes to
the antioxidative capacity of the body (Melia et
al. 1996; McDuffie et al. 2002). Indeed, employ-
ing a short term orlistat therapy, we observed a
dramatic decrease in levels of vitamins A and E.
Fat soluble antioxidant vitamins inactivate the
toxic lipid peroxidation (Granado et al. 1998) and
prevent the damage to body cell membranes
(Diplock 1991).
Exercise training has been recognized as an
important component of obesity treatment regi-
men. Our results confirmed that a combination of
orlistat and aerobic exercise training appears to
significantly reduce fat mass, reflecting increases
in fat utilization (Tremblay et al. 1991). There

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Orlistat Therapy and Oxidative Stress317
are several lines of evidence suggesting that exer-
cise training is associated with activation of anti-
oxidant enzymes in specific tissues, reduced oxi-
dative stress and lipid peroxidation tissues (Spina
et al. 1996; Marzatico et al. 1997; Miyazaki et al.
2001; Gunduz et al. 2004). That is, trained sub-
ject can perform higher work rate exercise with
less oxidative stress (Leaf et al. 1999). Our find-
ing showed that aerobic exercise training as an
adjunct to the orlistat therapy aids in better coping
with oxidative stress in obese patients, as indicat-
ed in marked decrease in resting MDA (Table 2),
despite that acute exercise has been shown to
cause increase in MDA levels (Marzatico et al.
1997).
It is important to emphasize that weight loss
without improvement in oxidative capacity may
not provide adequate level of health benefits for
obese patients who have high oxidative stress. By
achieving weight loss associated with higher fat
mass loss and improved oxidative status as indi-
cated by decreased MDA, aerobic exercise train-
ing as an adjunct to orlistat therapy may provide
further benefits in obesity management.
Considering marked decreases in antioxidant vita-
mins and high oxidative stress following a short-
term orlistat therapy, one should include either in-
cluding additional vitamins to diet, which will
support to decreased oxidative system, or an aero-
bic exercise training program to reduce oxidative
stress. Consequently, the weight loss strategies
should be aimed to ameliorate oxidative stress in
addition to weight loss in obese patients.
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