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International Journal of Sport Nutrition and Exercise Metabolism, 2011
© 2011 Human Kinetics, Inc.
Trabelsi, Zeghal, and Hakim are with the Laboratory of Phar-
macology, University of Sfax, Sfax, Tunisia. el Abed is with
the Laboratory of Cardiocirculatory, Respiratory, Metabolic,
and Hormonal Adaptations to Muscular Exercise, Faculty of
Medicine Ibn El Jazzar, Sousse, Tunisia. Stannard is with the
Inst. of Food, Nutrition and Human Health, Massey Univer-
sity, Massey, New Zealand. Jammoussi is with the Dept. of
Biochemistry, Hedi Chaker University Hospital, Sfax, Tunisia.
Effects of Fed- Versus Fasted-State Aerobic Training
During Ramadan on Body Composition and Some
Metabolic Parameters in Physically Active Men
Khaled Trabelsi, Kais el Abed, Stephen R. Stannard, Kamel Jammoussi,
Khaled M. Zeghal, and Ahmed Hakim
The aim of this study was to evaluate the effects of aerobic training in a fasted versus a fed state during Rama-
dan on body composition and metabolic parameters in physically active men. Nineteen men were allocated to
2 groups: 10 practicing aerobic training in a fasted state (FAST) and 9 training in an acutely fed state (FED)
during Ramadan. All subjects visited the laboratory for a total of 4 sessions on the following occasions: 3
days before Ramadan (Bef-R), the 15th day of Ramadan; the 29th day of Ramadan (End-R), and 21 days
after Ramadan. During each session, subjects underwent anthropometric measurement, completed a dietary
questionnaire, and provided fasting blood and urine samples. Body weight decreased in FAST and FED by
1.9% (p < .001) and 2.6% (p = .046), respectively. Body fat percentage decreased only in FAST by 6.2% (p =
.016). FAST experienced an increase in the following parameters from Bef-R to End-R: urine specic gravity
(0.64%, p = .012), urea (8.7%, p < .001), creatinine (7.5%, p < .001), uric acid (12.7%, p < .001), sodium
(1.9%, p = .003), chloride (2.6%, p < .001), and high-density lipoprotein cholesterol (27.3%, p < .001). Of
these parameters, only creatinine increased (5.8%, p = .004) in FED. Creatinine clearance values of FAST
decreased by 8.9% (p < .001) and by 7.6% in FED (p = .01) from Bef-R to End-R. The authors conclude that
aerobic training in a fasted state lowers body weight and body fat percentage. In contrast, fed aerobic training
decreases only body weight. In addition, Ramadan fasting induced change in some metabolic parameters in
FAST, but these changes were absent in FED.
Keywords: aerobic exercise, dehydration, body fat percentage, Islamic fasting
Ramadan is the holiest month in the Islamic calendar.
The uniqueness of Ramadan is that food and uid intake
are concentrated into the hours between sunset and the
following sunrise (Wilson, Drust, & Reilly, 2009), so food
frequency (BaHammam, 2005) and quantity (Husain,
Duncan, Cheah, & Ch’ng, 1987) and uid intake (Bouhlel
et al., 2006) may be affected. Ramadan occurs 11 days
earlier every year and thus over time may occur in any
of the four seasons. Therefore, the length of the daily
fast during Ramadan varies from 11 to 18 hr in tropical
countries (Sakr, 1975). As a consequence of the 1 month
of repeated periodic food restriction that participation in
Ramadan incurs, reductions in caloric intake (Bouhlel
et al., 2006) and losses in body weight (Bouhlel et al.,
2006; Sweileh, Schnitzler, Hunter, & Davis, 1992) have
Many participants in Ramadan maintain physical
activity during the fasting month. Measurements of the
effect of Ramadan fasting on urinary markers of hydration
status in athletes are equivocal, showing both an increase
(Wilson et al., 2009) and no change in urine osmolarity
(Aziz, Slater, Hwa Chia, & The, in press) or specic
gravity (Shirreffs & Maughan, 2008) during Ramadan.
Several markers of renal function have also been studied
during Ramadan to investigate possible effects of periodic
uid restriction. Increases in creatinine and decreases in
urea concentration have been observed (Maughan et al.,
2008), although others (Ramadan, Telahoun, Al-Zaid, &
Barac-Nieto, 1999) report no change in either parameter.
Uric acid has been reported to increase in elite judoists
(Chaouachi, Chamari, Roky, Wong, Mbazaa, & Bartagi,
2008) but not change in soccer players (Maughan et al.,
2008) or physically active men (Ramadan et al., 1999).
Several studies have also examined the combined effects
of physical activity and Ramadan fasting on serum
electrolytes. Ramadan et al. noted an increase in serum
bicarbonate and sodium concentrations in sedentary
men but no change in either concentration in physically
2 Trabelsi et al.
active men, and Maughan et al. reported increased serum
potassium concentrations but no change in serum sodium
concentration. Clearly, the effects of continuing physical
activity through Ramadan on hydration status require
The interaction between participation in Ramadan
and exercise and subsequent effects on circulating metab-
olites are also poorly understood. Although a decrease
in resting serum glucose has been noted in moderately
trained men (Aziz, Wahid, Png, & Jesuvadian, 2010),
soccer players (Aziz et al., in press), and runners (Faye et
al., 2005), an absence of change has been reported in elite
rugby (Bouhlel et al., 2006) and soccer players (Maughan
et al., 2008). Total cholesterol (TC), high-density lipo-
protein cholesterol (HDL-C), and low-density lipoprotein
cholesterol (LDL-C) have each been shown to increase
in elite judoists (Chaouachi et al., 2008). However, only
free-fatty-acid levels have been shown to increase in
middle-distance runners (Chennaoui et al., 2009).
During Ramadan, physical training is often sched-
uled at night to avoid beginning training sessions in a
completely fasted state (Wilson et al., 2009), thereby
preventing dehydration and hypoglycemia. However, it
has been demonstrated that aerobic training in a fasted
state can stimulate adaptations in muscle cells to facilitate
energy production via fat oxidation (Stannard, Buckley,
Edge, & Thompson, 2010; Van Proeyen, Szlufcik, Niel-
ens, Ramaekers, & Hespel, 2011). In fact, aerobic train-
ing in a fasted state increases muscle oxidative capacity
(Stannard et al., 2010) and at the same time enhances
exercise-induced net intramyocellular lipid degradation
(Van Proeyen et al., 2011). In addition, aerobic training
can prevent the development of an exercise-induced drop
in blood glucose concentration (Van Proeyen et al., 2011).
This begs the question as to whether training during
the day during Ramadan, although putting the athlete
at greater risk of dehydration and hypoglycemia, might
accelerate adaptations to training and ultimately result in
improved physical performance.
Currently, published studies that have investigated
the effects of aerobic exercise during Ramadan on body
composition and biochemical parameters of physically
active men have not also had a control group that did
equivalent exercise in the fed state (Aziz et al., 2010;
Ramadan et al., 1999; Stannard & Thompson, 2008).
Thus, any specic effects of training while fasted cannot
be properly identied. Indeed, this lack of control may
explain the varying observations in published studies
The aim of this study was to evaluate the effects of
aerobic training during Ramadan fasting on body compo-
sition and metabolic parameters of physically active men
and to ascertain whether there are differences between
the effects of aerobic training during the day (in a fasted
state) and aerobic training at night (in a fed state) regard-
ing body composition and selected metabolic parameters.
Nineteen physically active men were recruited into the
study and randomly allocated to two groups: Ten partici-
pants trained in a fasted state (FAST), and 9 trained in a
fed state (FED) during Ramadan. Each subject regularly
performed continuous aerobic exercise at least three
times/week but did not participate in formal competi-
tive sport. The training sessions consisted of one session
of cycling, one session of running, and one session of
rowing on a cycle ergometer (Sapilo, Italy) equipped with
a heart-rate monitor. One subject in FED also practiced
swimming equipped with a heart-rate monitor (Polar,
Finland). Each training session lasted 40–60 min. The
aerobic-training intensity was equivalent to 60–80% of
maximum heart rate and was supervised by the investi-
gators. Subjects were nonsmokers and did not use other
substances that would affect the study outcomes. Sub-
jects’ descriptive characteristics are provided in Table 1.
Before enrolling in the study, subjects were informed
of the experimental procedures and potential risks
associated with participation; however, they were not
informed of the study purpose. Each subject provided
written consent in accordance with the Declaration of
Helsinki. The study was approved by the research ethics
committee of the Faculty of Medicine of the University
of Sfax, Sfax, Tunisia.
Ramadan began on August 10 and ended on September 9,
2010. The average duration of the fast was approximately
15 hr. The study was conducted in Tunisia, where daytime
temperatures were 30–35 °C and relative humidity was
Subjects visited the laboratory on four separate
occasions: 3 days before Ramadan (Bef-R), the 15th
Table 1 Descriptive Characteristics, M ± SD
Age (years) 26.6 ± 3.0 27.6 ± 1.8
Weight (kg) 79.2 ± 3.0 80.5 ± 4.6
Height (cm) 180.0 ± 6.4 176.0 ± 3.2
Body-mass index (kg/m2) 24.6 ± 1.4 24.5 ± 1.6
Body fat % 19.4 ± 1.3 19.3 ± 1.2
Lean body mass (kg) 63.8 ± 3.0 65.0 ± 3.9
Years aerobic training 1.6 ± 0.7 1.7 ± 0.2
Aerobic training hr/week 3.0 ± 0.6 2.8 ± 0.5
VO2max (ml · min–1 · kg–1) 44.6 ± 4.2 45.9 ± 2.6
Note. FAST = subjects training in a fasted state; FED = subjects training
in a fed state; VO2max = maximal oxygen consumption.
Fed- vs. Fasted-State Training During Ramadan 3
day of Ramadan (Mid-R), the 29th day of Ramadan
(End-R), and 21 days after Ramadan (Post-R). In the
morning of each visit (approximately 10:30 a.m.), they
underwent anthropometric measurements, completed a
dietary questionnaire, and provided fasting blood and
urine samples. They were instructed to not consume any
food or calorie-containing beverage after 11:00 p.m. on
the day before each visit. During the 2 weeks before and
after the beginning of Ramadan, subjects recorded their
exercise sessions along with their rating of perceived
exertion (RPE) on the Borg scale (Borg, 1985; Table 2)
in a log book. All subjects were familiarized with the use
of the RPE scale before the commencement of the study.
During Ramadan, exercise sessions of FAST occurred in
the late afternoon (between 4:00 and 6:00 p.m.) and those
of FED occurred at night (between 9:30 and 10:30 p.m.)
after the break of fasting. Neither RPE nor the duration
of the exercise sessions changed in either FAST or FED
throughout the study. In addition, there were no differ-
ences in RPE or the duration of exercise between FAST
and FED at any time period.
Body weight was measured to the nearest 100 g using a
calibrated electronic scale (Seca Instruments Ltd., Ger-
many), and height was measured to the nearest 5 mm
using a stadiometer. Skinfold thickness was measured
using calibrated Harpenden calipers (Harpenden, UK) at
four standardized sites (biceps, triceps, subscapula, and
suprailium). Body fat percentage (BF%) was estimated
from skinfold measures using a previously published
algorithm (Durnin & Womersley, 1974). Lean body mass
was calculated as body weight minus body fat mass.
Dietary Intake Analysis
Subjects were instructed to record all food and bever-
ages consumed during the week before Ramadan and
then 3 days/week during Ramadan. Dietary records were
analyzed using the Bilnut program (Nutrisoft, Cerelles,
France) and the food-composition tables of the National
Institute of Statistics of Tunis (1978). Total water intake
was dened as the uid volume of consumed beverages
plus the water content of consumed foods.
Urine Specific Gravity
Urine specic gravity was assessed from 30 ml of urine
collected from each subject immediately before the
anthropometrical measurement. It was measured to the
nearest 0.001 unit with a hand refractometer (Atago,
During each session, venous blood samples (~5 ml) were
taken from an antecubital vein into a plain Vacutainer
tube. The blood was allowed to clot and then was cen-
trifuged at 1,500 g for 10 min at 4 °C. An aliquot of the
serum was used to measure serum glucose immediately
after the centrifugation step; the remainder was then
stored at –20 °C until subsequent analysis. An auto-
mated analyzer (Beckman Coulter Cx9, UK) measured
the concentrations of biochemical parameters using
the appropriate reactant. Blood glucose, uric acid, TC,
and triglycerides were determined using an enzymatic
colorimetric method (Biomérieux, France). Urea was
determined using an enzymatic method (Biomaghreb,
Tunisia). Creatinine concentrations were determined by
the Jaffé method. Creatinine clearance was determined
using the formula of Cockcroft and Gault (1976). Sodium,
potassium, and chloride concentrations were determined
by potentiometry. HDL-C concentrations were deter-
mined by immunoinhibition (Elitech, France) using
an automated analyzer (Flexor Vitalab, Netherlands).
LDL-C was calculated using the Friedewald formula
(Friedewald, Levy, & Fredrickson, 1972). The ratios
TC:HDL-C and LDL-C:HDL-C were derived from the
All statistical tests were performed using Statistica Soft-
ware (StatSoft, Paris, France). A 4 (periods) × 2 (FED or
FAST) repeated-measures analysis of variance (ANOVA)
Table 2 Rating of Perceived Exertion and Duration of Training Sessions Before and During
Ramadan, M ± SD
Between the Beginning
FAST FED FAST FED FAST FED
Rating of perceived exertion 12.9 ± 1.5 13.3 ± 2.3 13.3 ± 1.4 13.3 ± 1.6 13.1 ± 1.4 13.9 ± 1.7
Duration of session (min) 47.5 ± 11.6 52.1 ± 10.6 46.3 ± 10.6 51.3 ± 10.7 46.7 ± 10.7 49.3 ± 12.0
Note. Mid-R = middle of Ramadan, 15 days after beginning the fast; End-R = end of Ramadan, 30 days after beginning the fast; FAST = subjects
training in a fasted state; FED = subjects training in a fed state.
4 Trabelsi et al.
was applied. A Bonferroni post hoc test was performed
where appropriate. Differences between FAST and FED
were analyzed using nonpaired Student’s t test. Statisti-
cal signicance was set at p < .05. All data are expressed
as M ± SD.
Estimated mean daily energy intake before Ramadan
was similar between FED and FAST. Daily energy intake
during Ramadan did not change in both groups compared
with Bef-R. However, absolute daily energy intake was
signicantly higher in FED than in FAST during the
period between the beginning and the Mid-R (p < .001;
see Table 3).
Carbohydrate consumption during Ramadan did not
change in either group compared with Bef-R. However,
protein consumption in FAST increased by 10.7% (p
= .034) from Bef-R to Mid-R, and fat consumption of
FED increased by 7.7% (p = .049) from Bef-R to Mid-R.
Expressed as a percentage of daily macronutrient intake,
fat and carbohydrate intake did not change during Rama-
dan in either group. However, protein consumption in
FAST was signicantly higher during the period between
the beginning of Ramadan and Mid-R (p < .001) than
Body Weight and Body Composition
Compared with values at Bef-R, body weight of FAST
was 1.4% less at Mid-R (p = .004), 1.9% less at End-R
(p < .001). However, body weight of FED was 2.6% less
(p = .046) at End-R than at Bef-R. There was no differ-
ence in body weight between the two groups at any time
period in the study (see Table 4).
BF% in FAST decreased by 6.2% (p = .016) from
Bef-R to End-R. However, BF% of FED remained
unchanged during the whole period of the investigation.
There was no difference in BF% between the two groups
at each time period in the study. Lean body mass did not
change during the duration of the study in both groups.
Moreover, there were no differences in lean body mass
between the two groups at any time period.
Table 3 Dietary Intake Before and During Ramadan, M ± SD
Before Ramadan Between the Beginning and Mid-R Between Mid-R and End-R
FAST FED FAST FED FAST FED
Energy intake (kcal/day) 2,803 ± 511 2,795 ± 279 2,466 ± 143 3,056 ± 183### 2,726 ± 346 2,775 ± 312
Protein (g/day) 90.6 ± 18.4 96.3 ± 9.5 100.3 ± 11.2* 98.5 ± 7.0 93.0 ± 13.4 102.6 ± 7.0
Protein (%) 13.2 ± 2.8 13.9 ± 1.9 16.3 ± 2.0*** 13.0 ± 0.4### 13.8 ± 2.3 14.9 ± 1.6
Fat (g/day) 102.9 ± 27.4 103.5 ± 16.2 87.4 ± 8.4 111.5 ± 14.4* 103.0 ± 16.3 109.0 ± 8.9
Fat (%) 33.1 ± 6.0 34.1 ± 8.4 32.0 ± 3.1 32.9 ± 4.0### 34.0 ± 3.3 35.5 ± 1.6
Carbohydrate (g/day) 378.5 ± 93.7 369.6 ± 44.9 319.6 ± 44.2 414.8 ± 45.3### 357.1 ± 59.6 346 ± 57.9
Carbohydrate (%) 53.7 ± 6.2 52.9 ± 3.5 51.7 ± 4.9 54.2 ± 4.0 52.2 ± 2.4 49.6 ± 3.1
Total water intake (L/day) 4.0 ± 0.5 4.1 ± 0.5 3.4 ± 0.4* 3.5 ± 0.3 3.3 ± 0.2** 3.9 ± 0.5
Note. Mid-R = middle of Ramadan, 15 days after beginning the fast; End-R = end of Ramadan, 30 days after beginning the fast; FAST = subjects training in a
fasted state; FED = subjects training in a fed state.
Signicantly different from before Ramadan: *p < .05; **p < .01; ***p < .001. Signicantly different from FAST: ###p < .001.
Table 4 Body Weight and Body Composition During the Four Phases of the Study, M ± SD
Group Bef-R Mid-R End-R Post-R
Weight (kg) FAST 79.2 ± 3.0 78.1 ± 3.0* 77.7 ± 3.0*** 78.7 ± 2.7
FED 80.5 ± 4.6 79.1 ± 4.4 78.4 ± 4.6* 79.4 ± 4.8
Body fat % FAST 19.4 ± 1.3 18.6 ± 1.5 18.2 ± 0.7* 18.9 ± 1.5
FED 19.3 ± 1.2 18.8 ± 1.0 18.5 ± 0.9 18.9 ± 1.1
Lean body mass (kg) FAST 63.8 ± 3.0 63.6 ± 2.7 63.6 ± 2.7 63.9 ± 3.1
FED 65.0 ± 3.9 64.2 ± 3.6 63.9 ± 4.0 64.4 ± 4.1
Note. Bef-R = before Ramadan, 4 days before beginning the fast; Mid-R = middle of Ramadan, 15 days after beginning the fast; End-R = end of Ramadan,
30 days after beginning the fast; Post-R = after Ramadan, 21 days after the conclusion of the fast; FAST = subjects training in a fasted state; FED = subjects
training in a fed state.
Signicantly different from Bef-R: *p < .05; ***p < .001.
Fed- vs. Fasted-State Training During Ramadan 5
Urine Specific Gravity
Compared with values at Bef-R, urine specic gravity in
FAST was 0.81% higher at Mid-R (p < .001) and 0.64%
higher at End-R (p = .012). However, urine specic grav-
ity in FED did not change throughout the study. Urine
specic gravity of FAST was signicantly higher than
that of FED both at Mid-R (p = .007) and at End-R (p =
.038; see Table 5).
Urea, uric acid, and creatinine concentrations measured
at Bef-R were the same in FAST and FED. Urea values
in FAST were 8.7% higher at End-R than at Bef-R (p
< .001), whereas urea values of FED did not change
throughout the study. Compared with values at Bef-R,
creatinine values at End-R increased by 7.5% in FAST
(p < .001) and by 5.8% in FED (p = .004). Creatinine
clearance values of FAST decreased by 8.9% (p < .001)
and by 7.6% in FED (p = .01) from Bef-R to End-R.
Compared with values at Bef-R, uric acid values in FAST
were 10.4% higher at Mid-R (p = .011) and 12.7% larger
at End-R (p < .001). However, uric acid values in FED
remained unchanged over the whole period of the inves-
tigation. There were no differences in urea, creatinine,
creatinine clearance, and uric acid values between FED
and FAST at each time period (see Table 6).
There were no differences between FED and FAST in
serum sodium and chloride concentrations at Bef-R. At
Bef-R, serum potassium values in FED were higher than
those in FAST (p = .039). Compared with values at Bef-R,
serum sodium concentrations in FAST were 1.7% higher
at Mid-R (p = .008) and 1.9% higher at End-R (p = .003).
However, serum sodium concentrations in FED did not
change throughout the study. Compared with values at
Bef-R, serum chloride values in FAST were 2.6% larger
at End-R (p < .001). However, serum chloride values in
FED did not change throughout the study. Serum potas-
sium concentrations did not change throughout the study
in either group. No differences were found in sodium
and chloride values between FAST and FED at any time
period of the investigation.
Serum Lipid and Glucose
TC, triglycerides, HDL-C, and LDL-C values were not
different between the two groups at Bef-R. TC and tri-
glycerides did not change throughout the study in FAST
and FED. Compared with values at Bef-R, HDL-C of
FAST was 18.2% larger at Mid-R (p = .023) and 27.3%
larger at End-R (p < .001) and at Post-R (p = .012).
However, HDL-C values of FED did not change over
the whole period of the investigation. LDL-C values did
not change throughout the study in either group, and
there were no differences between the groups at any time
period. TC:HDL-C and LDL-C:HDL-C ratios were not
different between the two groups at Bef-R. Compared
with values at Bef-R, the TC:HDL-C ratio of FAST was
11.1% larger at Mid-R (p = .017) and 13.9% larger at
End-R (p = .003) and Post-R (p = .002). The TC:HDL-
C ratio of FED increased by 27.7% (p = .016) at End-R
compared with Bef-R. Compared with values at Bef-R,
the LDL-C:HDL-C ratio of FAST was 17.4% less at
Mid-R (p = .01) and 21.7% less at End-R (p = .001) and
Post-R (p = .001). The LDL-C:HDL-C ratio of FED
decreased by 25.3% at Mid-R (p = .05) and 30.4% (p =
.02) at End-R compared with Bef-R.
Serum glucose measured at Bef-R was the same in
FAST and FED. These did not change throughout the
study in either group.
Our results show that aerobic training undertaken in the
latter part of the daily fast of Ramadan (FAST) lowers
body weight and BF% in physically active men. In con-
trast, an equivalent amount of aerobic training undertaken
after the break of fast (FED) decreases only body weight.
In addition, Ramadan fasting induced some changes in
urinary and biochemical parameters in FAST that were
absent in FED.
With a cross-sectional training study design such
as employed in the current study, we cannot be sure that
each training group experienced exactly the same train-
ing load and thus that the differences in the dependent
variables between training groups are entirely a result of
Ramadan. However, several published studies indicate
that Ramadan fasting had no effect on the training load
Table 5 Urine Specific Gravity During the Four Phases of the
Study, M ± SD
Group Bef-R Mid-R End-R Post-R
FAST 1.022 ± 0.006 1.030 ± 0.003* 1.028 ± 0.004* 1.017 ± 0.003
FED 1.021 ± 0.006 1.020 ± 0.005## 1.022 ± 0.004# 1.022 ± 0.007
Note. Bef-R = before Ramadan, 4 days before beginning the fast; Mid-R = middle of Ramadan, 15
days after beginning the fast; End-R = end of Ramadan, 30 days after beginning the fast; Post-R =
after Ramadan, 21 days after the conclusion of the fast; FAST = subjects training in a fasted state;
FED = subjects training in a fed state.
Signicantly different from Bef-R: *p < .05. Signicantly different from FAST: #p < .05; ##p < .01.
6 Trabelsi et al.
of runners (Chennaoui et al., 2009), judoists (Chaoua-
chi et al., 2008), rugby players (Bouhlel et al., 2006),
and soccer players (Aziz, Chia, Singh & Faizul Wahid,
2011), showing that sportsmen maintain training volume
during Ramadan. In this context, it is worth remembering
that all participants have participated in Ramadan since
childhood, so they are very familiar with any associated
physical stresses. In addition, training was prescribed and
closely supervised, so we are condent that this indeed
was the case. Furthermore, although the variation (SD)
for training duration in each group is high (Table 2), the
mean training duration is similar.
The signicant decrease in BF% in FAST may be
a result—at least in part—of the increased utilization of
stored body fat. This has been previously reported (el
Ati, Beji, & Danguir, 1995; Ramadan et al., 1999) and
may be related to an increased ability to use lipids during
exercise (Bouhlel et al., 2006; Stannard & Thompson,
2008). However, the lack of change in BF% in FED might
simply reect a Type 2 error, so use of a noninvasive
method to measure changes in body fatness (e.g., DEXA)
in future studies of Ramadan is warranted. Dehydration,
as suggested by Bouhlel et al., could also be implicated
in the decreased body weight of both groups.
Urine specic gravity of FAST increased during
Ramadan, likely because of dehydration attributable to
reduced uid intake. In contrast, urine specic gravity in
FED did not change, nor did total water intake. Our nd-
Table 6 Serum Biochemical Parameters During the Four Phases of the Study, M ± SD
Group Bef-R Mid-R End-R Post-R
Urea (mmol/L), CV = 5.9% FAST 4.59 ± 0.36 4.68 ± 0.46 5.02 ± 0.28*** 4.54 ± 0.39
FED 4.62 ± 0.21 4.71 ± 0.47 4.88 ± 0.49 4.57 ± 0.28
Creatinine (μmol/L), CV = 3% FAST 87.80 ± 5.92 90.62 ± 3.20 94.42 ± 3.98*** 85.80 ± 4.82
FED 86.55 ± 4.16 89.22 ± 3.56 91.55 ± 3.39* 88.04 ± 2.29
Uric acid (μmol/L), CV = 2.9% FAST 298.50 ± 53.05 329.50 ± 47.22** 336.50 ± 39.49*** 302.10 ± 40.43
FED 283.67 ± 44.73 307.78 ± 39.42 309.67 ± 24.21 296.89 ± 29.63
Creatinine clearance (ml/min) FAST 128.48 ± 11.85 122.39 ± 8.24 116.99 ± 9.94*** 130.39 ± 7.80
FED 130.98 ± 8.51 124.68 ± 6.71 121.03 ± 6.24** 126.73 ± 5.45
Sodium (mmol/L), CV = 2.7% FAST 142.10 ± 2.13 144.50 ± 2.22** 144.80 ± 1.81* 142.90 ± 0.99
FED 141.67 ± 1.87 143.00 ± 1.50 143.89 ± 1.54 142.00 ± 1.66
Potassium (mmol/L), CV = 2.9% FAST 4.38 ± 0.36# 4.41 ± 0.35 4.45 ± 0.32 4.41 ± 0.32
FED 4.69 ± 0.21 4.57 ± 0.25 4.49 ± 0.39 4.50 ± 0.23
Chloride (mmol/L), CV = 2.8% FAST 102.70 ± 1.64 103.00 ± 1.33 105.40 ± 1.26*** 103.10 ± 1.79
FED 103.11 ± 1.96 103.67 ± 1.58 104.33 ± 1.22 103.78 ± 1.30
TG (mmol/L), CV = 2.9% FAST 0.69 ± 0.16 0.76 ± 0.17 0.77 ± 0.13 0.72 ± 0.13
FED 0.74 ± 0.13 0.77 ± 0.07 0.77 ± 0.11 0.76 ± 0.1
TC (mmol/L), CV = 3.1% FAST 3.92 ± 0.37 4.06 ± 0.30 4.08 ± 0.28 3.89 ± 0.34
FED 3.86 ± 0.38 3.91 ± 0.46 3.88 ± 0.31 3.81 ± 0.30
HDL-C (mmol/L), CV = 3% FAST 1.11 ± 0.24 1.30 ± 0.18* 1.38 ± 0.27*** 1.32 ± 0.24*
FED 1.09 ± 0.21 1.31 ± 0.11 1.36 ± 0.16 1.28 ± 0.18
LDL-C (mmol/L) FAST 2.46 ± 0.29 2.37 ± 0.28 2.31 ± 0.43 2.22 ± 0.38
FED 2.40 ± 0.42 2.22 ± 0.46 2.14 ± 0.37 2.15 ± 0.36
TC:HDL-C FAST 3.64 ± 0.68 3.16 ± 0.45* 3.07 ± 0.73** 3.06 ± 0.70**
FED 3.64 ± 0.67 3.01 ± 0.43 2.90 ± 0.50* 3.05 ± 0.58
LDL-C:HDL-C FAST 2.30 ± 0.56 1.86 ± 0.39** 1.77 ± 0.64** 1.77 ± 0.62**
FED 2.29 ± 0.61 1.71 ± 0.41* 1.61 ± 0.48* 1.74 ± 0.51
Glucose (mmol/L), CV = 2.3% FAST 4.89 ± 0.44 4.84 ± 0.55 4.81 ± 0.48 4.95 ± 0.50
FED 4.61 ± 0.52 4.68 ± 0.39 4.62 ± 0.31 4.81 ± 0.45
Note. Bef-R = before Ramadan, 4 days before beginning the fast; Mid-R = middle of Ramadan, 15 days after beginning the fast; End-R = end of
Ramadan, 30 days after beginning the fast; Post-R = after Ramadan, 21 days after the conclusion of the fast; CV = assay coefcient of variance;
FAST = subjects training in a fasted state; FED = subjects training in a fed state; TG = triglycerides; TC = total cholesterol; HDL-C = high-density
lipoprotein cholesterol; LDL-C = low-density lipoprotein cholesterol.
Signicantly different from Bef-R: *p < .05; **p < .01; ***p < .001. Signicantly different from FAST: #p < .05.
Fed- vs. Fasted-State Training During Ramadan 7
ings are dissonant with those of Shirreffs and Maughan
(2008), which may be a result of differences in exercise
regimen, climate, and uid intake.
The increases in markers of renal function in FAST
during Ramadan are most likely also caused by dehydra-
tion. Moreover, increased urea concentrations in FAST
may be explained by increased protein breakdown after
exercise sessions or decreased renal blood ow. Some
investigators have also suggested that increased urea
concentrations may be caused by exercise-induced energy
expenditure and reduced energy intake (Degoutte et al.,
2006). However, this suggestion can be excluded because
energy intake remained unchanged during Ramadan
compared with pre-Ramadan.
For FAST, dehydration likely led to the elevations of
creatinine and creatinine clearance values during Rama-
dan, indicating that renal function was impaired during
Ramadan. Similarly, uric acid increased in FAST during
Ramadan. Our results are consistent with those of Cha-
ouachi et al. (2008), who attributed increased uric acid
levels to dehydration and increased protein breakdown.
Our finding that serum sodium concentrations
increased in response to Ramadan fasting in FAST is con-
trary to the lack of change reported by other investigations
(Maughan et al. 2008; Ramadan et al. 1999). Similarly,
serum chloride concentrations increased only in FAST
during Ramadan, which was likely a consequence of both
dehydration and elevations in serum sodium (Anagnos-
topoulos, Edelman, Planelles, Teulon, & Thomas, 1984).
Because of the dehydration and the elevations in serum
sodium that occurred in FAST, one might expect that
increases in serum potassium concentrations would also
be observed, but this was not the case.
During this study, we used a combination of mark-
ers, and in addition to body mass to indicate hydration
status, we used urinary and blood-based markers. The
state of dehydration noted in FAST was absent in FED.
This nding can be attributed to adequate uid intake
after break of fast and during training sessions.
HDL-C increased during Ramadan in both groups,
a nding that was also observed in the study conducted
by Chaouachi et al. (2008). However, mechanism(s) by
which fasting increases HDL-C are not clear, although
loss of weight may increase HDL-C (Al Hourani, Atoum,
Akel, Hijjawi, & Awawdeh, 2009). LDL-C remained
unchanged during Ramadan in FAST and FED. Our
results do not agree with those of Chaouachi et al., which
indicate an increase in LDL-C in elite judoists. We sug-
gested an absence of change in the dietary saturated fat
intake to explain our ndings (Mattson & Grundy, 1985).
In conclusion, Ramadan fasting and aerobic exercise
practiced in a fasted state can be combined effectively to
reduce body weight and body fat, as well as improving
lipid proles. Body composition and hydration status,
however, may be inuenced by the timing of that train-
ing during Ramadan. Individuals engaging in aerobic
exercise during Ramadan should drink plentiful amounts
of uid during the nighttime to compensate for the dehy-
dration that occurs during daylight hours.
The authors would like to thank the subjects for their efforts,
commitment, and enthusiasm throughout the study.
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