Ramadan fasting, observed by millions worldwide, has long been associated not only with spiritual renewal but also with potential physiological benefits. Despite widespread practice, the scientific understanding of how Ramadan fasting (RF) impacts anthropometric measures and body composition has remained fragmented and inconclusive. A comprehensive new study published in International Journal of Obesity now sheds light on these effects, offering a systematic and data-driven analysis of how fasting during Ramadan influences physical health metrics over time.
Drawing from a vast pool of evidence, researchers aggregated data from 54 distinct studies spanning over three decades and involving nearly 3,000 healthy adult participants across 21 countries. This meta-analysis, which covers research from 1987 to 2024, marks one of the most exhaustive examinations to date into the physiological changes induced by intermittent fasting specifically within the context of Ramadan’s unique fasting regimen. The findings reveal nuanced temporal patterns in changes to weight, body mass index (BMI), fat mass, and other key measures.
One of the focal points of the study is the biphasic effect of Ramadan fasting on body weight and BMI. The data indicate that reductions in these parameters are not immediate but begin to emerge in the second and third weeks of the fasting period. Interestingly, the most pronounced decreases occur in the first week following Ramadan’s conclusion, suggesting a lag in physiological responses related to feeding cycles and metabolic adjustments. However, this trend is transient, with weight and BMI gradually reverting to baseline levels in the subsequent weeks.
Beyond weight alone, the study considers multiple anthropometric indicators such as waist circumference (WC), hip circumference (HC), and the waist-to-hip ratio (WHR), all of which serve as important predictors of metabolic health and cardiovascular risk. Significant reductions in WC and HC were observed predominantly in the later stages of Ramadan and the first week after fasting, with WHR showing more modest changes. These findings provide valuable insights into fat distribution changes that can occur with intermittent fasting, highlighting potential reductions in central adiposity which is closely linked to metabolic syndrome.
The research also delves deeply into alterations in body composition, differentiating between absolute fat mass (FM), fat percentage (FP), fat-free mass (FFM), and total body water (TBW). Ramadan fasting was found to induce a small but statistically significant reduction in absolute FM and FP during the third and fourth weeks of fasting. This suggests that RF primarily targets adipose tissue rather than lean muscle mass or hydration status. Notably, FFM and TBW remained stable throughout the fasting period, signaling that Ramadan fasting does not adversely affect muscle mass or overall hydration in healthy adults.
These results carry profound implications for both clinicians and individuals interested in leveraging intermittent fasting for health optimization. The transient nature of these anthropometric and body composition changes underscores the challenge of achieving lasting benefits without sustained lifestyle modifications. The study emphasizes the necessity for continued behavioral strategies post-Ramadan to maintain the weight loss and fat reduction benefits initiated during fasting.
The physiological mechanisms underlying these observations are likely multifactorial. The interplay between caloric restriction during daylight hours, altered circadian rhythms, hormonal fluctuations such as changes in insulin and cortisol, and shifts in energy metabolism collectively contribute to the observed patterns. The delayed nadir in weight loss post-Ramadan could be reflective of metabolic adaptations that continue to influence substrate utilization even after fasting ceases.
Furthermore, the cultural and regional diversity encompassed in the study adds robustness to the findings. Conducted across diverse populations—from Middle Eastern to Southeast Asian regions—this meta-analysis accounts for variability in fasting durations, dietary practices, and environmental conditions, providing a globally relevant perspective. Despite heterogeneity in study designs and participant demographics, the consistency in trends strengthens confidence in the generalizability of the conclusions.
Additionally, the results hint at a subtle but essential distinction between intermittent fasting during Ramadan and other forms of caloric restriction or diet-induced weight loss. Unlike continuous calorie reduction, Ramadan fasting involves daily cycles of food abstinence and refeeding, which may trigger unique metabolic responses, including phases of fat mobilization without significant lean tissue catabolism. This could explain the maintenance of fat-free mass and hydration status, factors often compromised in rapid or extreme weight loss regimens.
This study’s nuanced timeline analysis, breaking down changes across the fasting period and afterward, highlights the dynamic nature of the body’s response to Ramadan fasting. Such temporal granularity enables a better understanding of when interventions might be most beneficial or when reinforcements might be necessary to preserve gains. For example, the peak reductions observed post-Ramadan suggest an optimal window for behavioral reinforcement to consolidate benefits.
Moreover, this research opens avenues for future investigations, particularly regarding long-term strategies to sustain weight and fat mass reductions initiated during Ramadan. The transient effects point to a gap between short-term fasting benefits and prolonged health improvements, signaling the need for complementary nutritional and physical activity interventions outside of the fasting month.
From a public health perspective, these insights can inform guidelines tailored to Muslim populations who observe Ramadan and also suffer from increases in obesity and related metabolic disorders globally. Understanding the physiological underpinnings and timeline of changes could inspire culturally sensitive programs that capitalize on Ramadan’s fasting framework to promote healthier habits year-round.
In essence, this extensive meta-analysis bridges significant gaps in the literature, translating complex physiological responses into practical knowledge. It reframes Ramadan fasting not simply as a spiritual practice but also as a physiological stimulus capable of transiently modulating body composition and anthropometric measures.
As intermittent fasting continues to gain popularity worldwide, this study serves as a crucial contribution, revealing the temporal and compositional specifics of fasting-induced changes. It guides both researchers and clinicians toward optimizing fasting protocols and underscores the importance of adjunct measures to sustain improvements.
Ultimately, while the weight and fat reductions observed during Ramadan fasting are modest and short-lived, the findings encourage harnessing this period as a springboard for longer-term health gains. Establishing strategies to maintain and extend these effects beyond Ramadan may provide a powerful, culturally meaningful intervention against the backdrop of rising obesity rates.
This pioneering investigation thus not only decodes the physiological impact of Ramadan fasting but also sets the stage for evolving fasting practices into holistic lifestyle interventions, marrying tradition with cutting-edge nutritional science.
Subject of Research: The impact of Ramadan fasting on anthropometric measures and body composition in healthy adults across different time points during and after Ramadan.
Article Title: The effect of Ramadan fasting on anthropometric and body composition of healthy adults within different time points: A systematic review and meta-analysis.
Article References:
Wulandari, F., Naim, A.J., Putri, U.M.P. et al. The effect of Ramadan fasting on anthropometric and body composition of healthy adults within different time points: A systematic review and meta-analysis. Int J Obes (2025). https://doi.org/10.1038/s41366-025-01785-7
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