Intermittent fasting during Ramadan causes transient loss of body fat and improvement in insulin sensitivity

Abstract

Background. periods of voluntary abstinence from food, such as intermittent fasting, has been practiced since earliest antiquity by people around the globe. The benefits of restricting energy intake severely for two days a week while eating normally the rest of week has been popularised. However, the evidence for the health benefits of fasting in humans is often extrapolated from animal studies, based on observational data on religious fasting, or derived from experimental studies. Furthermore, periods of prolonged daily fasting may be especially beneficial to improving sensitivity to insulin. However, whether the reduced water consumption and physical activity during ramadan may mitigate these health is less well studied. Therefore, This study tested the hypothesis that prolonged daily fasting, for greater than 12 h in a 24 h cycle, without calorie restriction, reduces hyperinsulinaemia even in the absence of weight loss.Methods. All participants were non-Caucasians males. The study consisted of three phases: phase1:2 visit in the 10 days prior to the start of ramadan, phase 2:3 visits (1 per week) during the 30 days of ramadan and phase 3:1 vist one month after ramadan, when normal patterns of eating and exercising had been resumed. At each study day subjects attended twice, once in the morning (between 08:30 and 10 AM) and once in the afternoon (between 2.00 to 4.30 PM). All subjects completed a questionnair detailing age, smoking habits, medical history, sleeping patterns, dietary intake and training schedule. The studies were approved by National research Ethics Committee and written informed consent was obtained for all participants. 10 subjects completed the study.Weight (Kg) and body composition was measured by electrical bio-impedance (Tanita MC-980 MA) with light cloths at each AM visit. Height (m) was measured on the first visit and BMI was calculated by using formula body weight (kilometres) divided by height (meters) squared. All the participants remained seated for 10 minutes prior to determination of systolic and diastolic blood pressure, and heart rate using an automatic digital blood pressure monitor from the non-dominate arm and mean atrial BP (MAP). blood samples were drawn at all occasions through the ante cubical vein into tubes containing no anti-coagulant or EDTA, separated and stored until analysis. Plasma glucose (mmol/L), serum triglycerides (mmol/L), high density lipoprotein cholestrol (mmol/L), total and direct bilirubin (umol/L), Alanine transaminase (U/L), Aspartate aminotransferase (U/L), urea (mmol/L), uric acid (umol/L), and creatinine (umol/L) concentrations were determined on a chemistry analyser. Insulin (mU/L) concentrations were determined by ELISA. Results are experssed as mean and standard deviattion for normally distributed data and median and iterquartile ranges for skewed data. Significance was defined as P < 0.05.Results. There was significant reduction in body weight during the 2nd and 3rd weeks of ramadan. This weight loss was not sustained in the period immediately following the fasting months as all weight loss was regaind. Body mass index followed the same pattern as body weight. Body fat, both % and mass, decreased soon after the start of fasting (within 2 - 3 days) and was sustaind through the three ramadan testing phases. However, like body weight this loss in body fat was regained in the period immediately after normal eating patterns were resumed.There were no significant changes in muscle mass or body water as a consequence of fasting during Ramadan.There were no significant changes in blood pressure, pulse or basal metabolice rate throughout the entire study.Please (see Table 1) for details.Of note is that all participants were hyperinsulinaemic through the periods of testing prior to and after the cessation of the fasting month. However, during the fasting period insulin levels were significatly reduced. Similar trends were also apparent for alanine transaminase and triglycerides (see Table 2). No changes were seen for all other measured variables. All subjects remained euglycaemic and normotentive.Conclusions. This study shows, for the first time that, prolonged periods of fasting during the day, even without reducing overall daily calorie intake, favours loss of body fat, while preserving muscle mass. This was accompanied by significant improvement in systemic hyperinsulinaemia and indices of liver function.