We examined the variations in eating behavior, appetite ratings, satiety efficiency, energy expenditure, anthropometric and metabolic profile markers prior to, during as well as 1 and 4 months after Ramadan in normal-weight and obese men. Anthropometric, energy expenditure (indirect calorimetry and accelerometry), metabolic (fasting blood sample), appetite (visual analogue scales), and eating behavior (Three-Factor Eating Questionnaire) measurements were performed in 10 normal-weight (age: 25.2 ± 4.7 years; BMI: 24.4 ± 1.9 kg/m2) and 10 obese (age: 27.0 ± 4.5 years; BMI: 34.8 ± 3.7 kg/m2) men. The satiety quotient (SQ) was calculated 180 minutes after breakfast consumption. All anthropometric variables, as well as resting and total energy expenditure, were greater in obese compared to normal-weight participants (
Many studies have assessed the effects of the Ramadan fast on different metabolic and anthropometric parameters, but have noted conflicting results. More specifically, some studies noted decreases in body weight and body mass index (BMI) during the Ramadan fast [
With regards to metabolic profile markers, some studies noted improvements in metabolic profiles (i.e., lower levels of fasting cholesterol, glucose, and triglyceride) during the Ramadan fast [
While many studies have assessed potential variations in different metabolic and anthropometric parameters prior to, during, and/or up to 1 month after Ramadan, none have reassessed these variables four months later in order to evaluate whether potential changes in these variables may persist over a longer period of time. Furthermore, the assessment of different appetite, anthropometric and metabolic profile markers in normal-weight and obese individuals across the Ramadan fast is scarce, with only 1 study previously comparing the changes in body weight and the metabolic profile of normal-weight and obese men during the Ramadan fast [
Ten normal-weight (BMI ≤ 27 kg/m²) and ten obese (BMI ≥ 30 kg/m²) men took part in the present study. These BMI cut-off points were based on those established by The National Institutes of Health Consensus Development Panel on the Health Implications of Obesity [
Different measurements were taken at baseline (before the onset of Ramadan; session 1), 2 weeks into the Ramadan fast (session 2), 1 week before the end of the Ramadan fast (session 3), 3-4 weeks following the end of the Ramadan fast (session 4), and finally 16–20 weeks following the end of the Ramadan fast (session 5). Measurements were taken over 5 hours during sessions 1, 4, and 5. These sessions began at 7:30 a.m. for all participants. As for sessions 2 and 3, which lasted 1.5 hours each, measurements were taken from a maximum of 5 participants over the course of 1 morning, and their start times were staggered between 8:30 a.m. and 10:30 a.m. (i.e., 2, 2, and 1 participants started measurements at 8:30 a.m., 9:30 a.m. and 10:30 a.m., respectively, during sessions 2 and 3). Anthropometric measurements were performed during each session. REE and the thermic effect of food (TEF) were assessed during sessions 1, 4, and 5. Habitual PAEE was assessed for seven days during sessions 1, 2, 4, and 5. The participants’ appetite sensations were recorded every 30 minutes for 3 hours following the consumption of a standardized breakfast with visual analogue scales (VAS) [
Participants were weighed to the nearest 0.1 kg with a BWB-800AS digital scale. Standing height was measured to the nearest centimeter using a wall stadiometer, Tanita HR-100 height rod, without shoes (Tanita Corporation of America, Inc.). Body composition (total fat mass and total fat-free mass) was assessed with DXA (Lunar Prodigy, General Electric, Madison, WI, USA). The coefficient of variation and correlation for body fat percentage assessed in 12 healthy participants tested in our laboratory were 1.8% and
REE was evaluated with indirect calorimetry (Deltatrac II metabolic cart, Sensor Medics Corporation, Yorba Linda, California, USA) following an overnight fast. The TEF was evaluated with indirect calorimetry for 1.5 hours over a 3-hour time span (i.e., 3 rotations of 30 minutes of measurements with 30 minutes of no measurements) following the consumption of a standardized breakfast. The coefficient of variation and correlation for REE measured with the Deltatrac II metabolic cart were 2.3% and
The TFEQ [
A standardized breakfast was served at 9:30 a.m. during sessions 1, 4, and 5. This breakfast contained whole-wheat bread (80 grams), peanut butter (36 grams), strawberry jam (32 grams), cheddar cheese (21 grams) and orange juice (250 grams), and had a caloric content of 592 kilocalories and a food quotient of 0.89 (57% carbohydrates, 13% proteins and 30% lipids). The participants were instructed to consume the entire meal in 15 minutes. Appetite sensations were recorded with VAS before, immediately after (time 0), and every 30 minutes (30, 60, 90, 120, 150, and 180 minutes) for 3 hours following breakfast consumption. The 150 mm VAS [
The satiety quotient (SQ), which is a valid marker of satiety efficiency in response to a standardized meal [
It is important to note that SQ calculation for the fullness rating is reversed (i.e., mean postmeal fullness rating − fasting fullness rating). The mean SQ, determined as the mean value of SQ scores for the 4 appetite sensations, was also calculated. The SQ calculation has a good reliability when assessed under controlled laboratory conditions, with the intraclass correlation coefficient value (
A single blood sample was drawn from the antecubital vein of the nondominant arm following an overnight fast to determine plasma levels of total cholesterol, HDL-C, LDL-C, triglyceride, glucose, insulin, and Apo-B. Blood samples were placed into a tube containing Ethylenediaminetetraacetic acid (EDTA) and were centrifuged at 3500 rpm at 4°C immediately after the blood was drawn and stored at −80°C until assayed. Plasma insulin concentrations were determined by radioimmunoassay using 125I-labeled human insulin and a human insulin antiserum (Millipore, St. Charles, Missouri). Plasma glucose concentrations were determined with spectrophotometric analysis after converting the glucose to glucose-6-phosphate via hexokinase (Sigma-Aldrich Canada Ltd., Oakville, Ontario, Canada; Fisher Scientific Limited, Nepean, Ontario, Canada). Homeostasis model assessment-insulin resistance (HOMA-IR) was estimated with the following equation: HOMA-IR = (fasting glucose * fasting insulin)/22.5. Total cholesterol, HDL-C, and triglyceride levels were analyzed with the Vitros 950 immunoassay analyzer (Ortho Clinical Diagnostics; Johnson & Johnson Company, Markham, Ontario, Canada) at a wavelength of 540 nanometers. These same variables were used in the Friedewald formula to determine LDL-C levels [
Statistical analyses were performed using SPSS (version 17.0; SPSS Inc., Chicago, IL). Two-way repeated measures ANOVA with BMI status (normal-weight and obese) as the between-subject factor were used to determine the main effects of time (baseline, during the Ramadan fast, and after Ramadan fast) on anthropometric parameters (body weight, waist circumference, body fat mass and body fat-free mass), TEE, REE, TEF, PAEE, and metabolic profile markers (total cholesterol, HDL-C, LDL-C, triglyceride, glucose, insulin, Apo-B and HOMA-IR), as well as TFEQ scores (dietary restraint, disinhibition eating behavior trait and feelings of hunger). Paired
Bivariate Spearman correlations were used to assess whether the changes in metabolic profile markers (delta sessions 1-2, 1–5, and 2–5) and TFEQ scores (delta sessions 1–3, 1–5, and 3–5), as well as fasting and postmeal AUC appetite ratings and SQ (delta sessions 1–5), were associated with changes in anthropometric parameters between these same sessions. Data are presented as means ± standard deviations, and effects with
The variations in anthropometric parameters across sessions and between BMI groups are presented in Table
Variations in anthropometry, energy expenditure, and Three-Factor Eating Questionnaire variables across time, and between BMI status groups.
Session 1 | Session 2 | Session 3 | Session 4 | Session 5 | Repeated-measures ANOVA | ||||||||
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Mean | SD | Mean | SD | Mean | SD | Mean | SD | Mean | SD | Time effect | Group effect | Time * group interaction | |
Body weight (kg) | |||||||||||||
Normal-weight | 72.8 | 9.2 | 72.2 | 9.4 | 71.8 | 9.4 | 72.1 | 9.6 | 72.9 | 10.5 |
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Obese | 107.9 | 15.7 | 106.0 | 15.1 | 105.3 | 15.4 | 105.0 | 15.1 | 105.7 | 14.8 | |||
Waist circumference (cm) | |||||||||||||
Normal-weight | 82.6 | 6.3 | 82.3 | 7.2 | 83.3 | 7.8 | 82.6 | 7.6 | 84.8 | 8.4 |
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Obese | 113.3 | 10.8 | 110.7 | 11.1 | 111.9 | 11.2 | 110.4 | 12.2 | 110.8 | 11.6 | |||
Fat mass (kg) | |||||||||||||
Normal-weight | 17.6 | 4.2 | 17.7 | 4.6 | 17.6 | 4.5 | 17.4 | 4.9 | 18.1 | 5.4 |
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Obese | 39.1 | 10.3 | 39.2 | 10.4 | 37.7 | 9.6 | 37.8 | 9.7 | 36.9 | 9.1 | |||
Fat-free mass (kg) | |||||||||||||
Normal-weight | 55.1 | 5.9 | 54.3 | 5.7 | 54.1 | 5.8 | 54.6 | 5.7 | 54.0 | 6.5 |
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Obese | 68.2 | 9.4 | 66.3 | 9.2 | 67.1 | 9.5 | 67.0 | 8.6 | 68.6 | 10.0 | |||
REE (kcal) | |||||||||||||
Normal-weight | 1605 | 197 | NA | NA | NA | NA | 1559 | 244 | 1592 | 260 |
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Obese | 2132 | 389 | NA | NA | NA | NA | 2076 | 336 | 2143 | 317 | |||
TEF (kcal) | |||||||||||||
Normal-weight | 41 | 13 | NA | NA | NA | NA | 44 | 17 | 44 | 16 |
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Obese | 43 | 16 | NA | NA | NA | NA | 44 | 17 | 45 | 19 | |||
PAEE (kcal) | |||||||||||||
Normal-weight | 796 | 195 | 796 | 186 | NA | NA | 777 | 182 | 794 | 227 |
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Obese | 1015 | 444 | 945 | 310 | NA | NA | 1015 | 362 | 984 | 367 | |||
Total EE (kcal) | |||||||||||||
Normal-weight | 2442 | 320 | NA | NA | NA | NA | 2380 | 363 | 2431 | 443 |
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Obese | 3190 | 714 | NA | NA | NA | NA | 3135 | 511 | 3172 | 513 | |||
Dietary restraint score | |||||||||||||
Normal-weight | 9 | 3 | NA | NA | 12 | 3 | NA | NA | 9 | 2 |
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Obese | 8 | 4 | NA | NA | 9 | 4 | NA | NA | 8 | 4 | |||
Disinhibition eating behavior trait score | |||||||||||||
Normal-weight | 6 | 2 | NA | NA | 5 | 2 | NA | NA | 6 | 2 |
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Obese | 6 | 2 | NA | NA | 7 | 3 | NA | NA | 6 | 3 | |||
Feelings of hunger score | |||||||||||||
Normal-weight | 7 | 3 | NA | NA | 7 | 2 | NA | NA | 6 | 2 |
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Obese | 6 | 2 | NA | NA | 7 | 3 | NA | NA | 6 | 3 |
Session 1: baseline/before the onset of Ramadan.
Session 2: 2 weeks into the Ramadan fast.
Session 3: 1 week before the end of the Ramadan fast.
Session 4: 3-4 weeks following the end of the Ramadan fast.
Session 5: 16–20 weeks following the end of the Ramadan fast.
Note: SD: standard deviation; kg: kilogram; cm: centimeter; REE: resting energy expenditure; kcal: kilocalorie; TEF: thermic effect of food; PAEE: physical activity energy expenditure; EE: energy expenditure.
NA signifies that this measurement was not taken during this session.
No differences in HOMA-IR, insulin, HDL-C, and triglyceride levels were noted across sessions (Table
Variations in metabolic parameters across time and between BMI status groups.
Session 1 | Session 2 | Session 5 | Repeated-measures ANOVA | ||||||
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Mean | SD | Mean | SD | Mean | SD | Time effect | Group effect | Time * group interaction | |
Total cholesterol (mmol/L) | |||||||||
Normal-weight | 4.31 | 0.68 | 4.38 | 0.78 | 4.29 | 0.65 |
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Obese | 4.75 | 0.75 | 5.20 | 0.56 | 4.57 | 0.55 | |||
HDL-C (mmol/L) | |||||||||
Normal-weight | 1.19 | 0.21 | 1.17 | 0.21 | 1.22 | 0.27 |
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Obese | 1.01 | 0.17 | 1.10 | 0.17 | 1.07 | 0.16 | |||
LDL-C (mmol/L) | |||||||||
Normal-weight | 2.69 | 0.61 | 2.87 | 0.74 | 2.60 | 0.78 |
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Obese | 2.99 | 0.65 | 3.51 | 0.43 | 2.70 | 0.40 | |||
Triglyceride (mmol/L) | |||||||||
Normal-weight | 0.96 | 0.46 | 0.77 | 0.16 | 1.02 | 0.62 |
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Obese | 1.65 | 1.10 | 1.35 | 0.83 | 1.75 | 1.17 | |||
Glucose (mmol/L) | |||||||||
Normal-weight | 4.6 | 0.3 | 4.8 | 0.3 | 4.5 | 0.4 |
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Obese | 5.0 | 0.7 | 5.2 | 0.5 | 4.8 | 0.6 | |||
Insulin (pmol/L) | |||||||||
Normal-weight | 26.7 | 9.2 | 25.8 | 8.9 | 28.8 | 12.2 |
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Obese | 73.1 | 60.6 | 56.4 | 32.5 | 51.0 | 19.7 | |||
Apo-B (g/L) | |||||||||
Normal-weight | 0.77 | 0.13 | 0.80 | 0.16 | 0.80 | 0.17 |
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Obese* | 0.90 | 0.19 | 1.00 | 0.16 | 0.90 | 0.17 | |||
HOMA-IR (units) | |||||||||
Normal-weight | 5.4 | 1.8 | 5.5 | 2.0 | 5.9 | 2.7 |
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Obese | 17.7 | 18.5 | 13.5 | 8.4 | 10.9 | 4.7 |
Session 1: baseline/before the onset of Ramadan.
Session 2: 2 weeks into the Ramadan fast.
Session 3: 1 week before the end of the Ramadan fast.
Session 4: 3-4 weeks following the end of the Ramadan fast.
Session 5: 16–20 weeks following the end of the Ramadan fast.
Note: SD: standard deviation; mmol: millimole; L: litre; HDL-C: high-density lipoprotein cholesterol; LDL-C: low-density lipoprotein cholesterol; pmol: picomole; Apo-B: apolipoprotein B; g: gram; HOMA-IR: homeostatic model assessment-insulin resistance.
Table
Statistically significant correlations between changes in anthropometric parameters with delta metabolic markers, delta disinhibition eating behavior trait score, and delta dietary restraint score between different sessions.
Body weight (kg) | Waist circumference (cm) | Fat mass (kg) | Fat-free mass (kg) | |
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Total cholesterol (mmol/L) | ||||
Delta sessions 1 and 2 |
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Delta sessions 1 and 5 |
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LDL (mmol/L) | ||||
Delta sessions 1 and 5 |
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Triglyceride (mmol/L) | ||||
Delta sessions 1 and 5 |
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Glucose (mmol/L) | ||||
Delta sessions 1 and 5 |
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Insulin (pmol/L) | ||||
Delta sessions 1 and 5 |
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Delta sessions 2 and 5 |
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APB (g/L) | ||||
Delta sessions 2 and 5 |
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HOMA-IR (units) | ||||
Delta sessions 1 and 5 |
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Delta sessions 2 and 5 |
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Disinhibition eating behavior trait score | ||||
Delta sessions 1 and 3 |
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Dietary restraint score | ||||
Delta sessions 1 and 5 |
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Note: kg: kilogram; cm: centimeter; mmol: millimole; L: litre; pmol: picomole; g: gram; HOMA-IR: homeostatic model assessment-insulin resistance; mm: millimeter.
To our knowledge, this is the first study to evaluate eating behavior, appetite ratings, satiety efficiency, TEE, anthropometry, and different metabolic profile markers prior to, during as well as 1 and 4 months following the end of the Ramadan fast in normal-weight and obese men. Collectively, our results demonstrated that no changes in anthropometry, energy expenditure, appetite ratings, and SQ occurred across time, which does not support our initial hypothesis. Significant increases in Apo-B, glucose, total cholesterol, and LDL-C levels were noted during the Ramadan fast, which also does not support our hypotheses. Greater dietary restraint scores were noted at this time. Changes in body weight, waist circumference, and fat mass at baseline, during Ramadan, and 16–20 weeks following the Ramadan fast were positively associated with changes in most metabolic profile markers, whereas changes in fat-free mass were negatively associated with changes in total cholesterol and HOMA-IR. Lastly, delta disinhibition eating behavior trait scores were positively associated with changes in fat mass between baseline and the Ramadan fast, whereas delta dietary restraint scores were negatively associated with changes in fat-free mass between baseline and 16–20 weeks after Ramadan.
The noted increases in Apo-B, glucose, LDL-C, and total cholesterol levels are supported by 1 other study [
Ünalacak et al. [
No differences in REE, TEF, PAEE and TEE across time in normal-weight and obese participants were noted in the present study. These results are in agreement with other studies that also measured REE and PAEE in normal-weight men and women [
As for eating behavior, dietary restraint scores were significantly greater during the Ramadan fast, which may be expected as increases in dietary restraint scores were also found to be greater in regular dieters [
Lastly, no significant differences in appetite ratings and all measured SQ variables were noted across time in normal-weight and obese participants in the present study. To our knowledge, only one other study has previously assessed variations in appetite ratings throughout the day during the Ramadan fast, during the Ramadan feast (day 31; the day after the end of the Ramadan fast), and within 1 month after Ramadan [
The present findings are limited to a small sample size of normal-weight and obese men living in Canada, which limits generalizability to other populations (e.g., women and residents of other countries). Not all measurements were taken during each session, and the start of measurements during sessions 2 and 3 did vary between participants (range between 8:30 a.m. and 10:30 a.m.). Measurements of energy intake were taken with 7-day food diaries at baseline, during Ramadan and 16–20 weeks after Ramadan; however, based on the high degree of nonresponders (e.g., 7 participants did not complete the food diaries after Ramadan) and underreporters (e.g., underreporting was noted in 3 participants of the remaining 13 during session 5) in this cohort, we decided not to include these data in the analyses. Likewise, it is possible that potential differences in the types of meals consumed prior to, during, and following the Ramadan fast may have an impact on blood measurements, even though these measurements were taken in participants when fasted (i.e., following a 12-hour overnight fast in sessions 1 and 5, and an 8-hour fast in session 2). Only 1-day assessments of the measured outcomes were performed during each session, which does not account for normal day-to-day variations in these variables. Lastly, the correlations computed between changes in appetite ratings, TFEQ scores, anthropometry, and metabolic profile markers cannot infer causality.
In conclusion, we observed significant increases in Apo-B, glucose, total cholesterol, and LDL-C concentrations during the Ramadan fast in normal-weight and obese men. Dietary restraint scores were also greater during Ramadan. Lastly, changes in anthropometric parameters were related to changes in metabolic profiles, dietary restraint, and disinhibition eating behavior trait scores. Future studies would be needed to assess the longer-term effects of the Ramadan fast on measures of energy expenditure, anthropometry, appetite, and metabolic profiles, as changes in some of these parameters may only occur over many years.
The authors declare no conflict of interests regarding the publication of this paper.
Mohamed M. Mamlouk and Éric Doucet formulated the research questions and designed the study. Mohamed M. Mamlouk, Karine Duval, and Alexander Schwartz carried out the experiment. Jessica McNeil and Nelson Nardo Junior analyzed the data. All authors were involved in the writing of the paper and had final approval of the submitted and published version.
Jessica McNeil is a recipient of the Ontario Graduate Scholarship.