It is an important component of Islamic practice for healthy adult Muslims to fast from sunrise to sunset during the holy month of Ramadan. In addition, fluid intake, cigarette smoking, and medications are forbidden. Depending on the geographical location of those who are fasting during Ramadan, day fasting can vary from 11 to 22 hours. Islamic fasting during Ramadan does not require energy restriction; however, as the intake of food and fluid becomes less frequent, changes in body weight may occur.
A 2012 meta-analysis of 35 studies examined weight changes during Ramadan. Across these studies, participants’ ages ranged from 18 to 58 years; just more than half (52%) of studies were conducted with both males and females, 34% were conducted with only males, and 11% were conducted with only females. The authors of the review found statistically significant weight loss in 21 (60%) of the studies. When pooled, the studies in this meta-analysis showed a 1.24 kg weight reduction during the month of Ramadan fasting. Across 16 follow-up studies, the mean weight regained during the 2 weeks following Ramadan was 0.72 kg (95% CI, 0.32 to 1.13 kg).
A 2013 meta-analysis of 30 cohort studies that included healthy young men and women examined whether Ramadan fasting altered biomarkers in addition to weight. The primary finding of this meta-analysis was that after Ramadan fasting, LDL and fasting blood glucose levels were decreased in both sexes and also in the entire group compared with levels prior to Ramadan. In females, HDL cholesterol levels were significantly increased. In males, there was a significant decrease in weight, total cholesterol, and TGs. Some studies have reported that Ramadan fasts are associated with significantly lower concentrations of inflammatory markers, such as CRP, IL-6, and TNF-α.
Recent studies have shown that Ramadan fasting practiced by patients with type 2 diabetes for 15–21 days leads to a statistically and clinically significant reduction in hemoglobin A1c (HbA1c) levels of approximately 0.5 points, suggesting that glycemic control is improved substantially during Ramadan fasting in this population. Ramadan is the most common form of time-restricted feeding, and it results in transitory weight loss, with mixed evidence for improvements in metabolic markers. However, this feeding pattern is in biological opposition to human circadian rhythms and, therefore, unlikely to be pursued as a desirable weight-loss intervention.
(Adapted from: annualreviews.org)
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