Body Composition Dynamics and Weight Sustainability During Ramadan Fasting

Sustainability of weight loss remains a major challenge in obesity management, with many individuals experiencing partial or full weight regain after initial success. This abstract synthesizes current evidence on key determinants of long-term weight maintenance, emphasizing the interaction of physiological adaptation, behavioral adherence, and body-composition changes. A central barrier is metabolic adaptation (adaptive thermogenesis), where resting energy expenditure declines beyond what is expected from tissue loss and may persist during weight maintenance, creating a biological drive toward weight regain. Hormonal changes, including appetite-related signals such as ghrelin, further contribute to increased hunger and subsequent regain risk. Emerging evidence also links post–weight loss metabolic signatures (e.g., circulating metabolites) with later adiposity rebound, suggesting that underlying substrate metabolism influences the durability of fat loss. Behavioral and environmental factors strongly shape sustainability. Adherence to dietary strategies, self-monitoring, and sustained engagement with interventions predict better outcomes, while poor sleep and related cravings can undermine maintenance. Intermittent fasting (including time-restricted approaches) is often reported as easier to follow than continuous calorie restriction and may support cardiometabolic improvements; however, long-term sustainability and safety data remain limited, and evidence from Ramadan fasting contexts indicates that weight loss can be temporary without continued lifestyle modification post-fasting. Preservation of lean mass is a critical component of sustainable weight loss because muscle loss reduces energy expenditure and functional capacity, increasing vulnerability to regain. Accordingly, strategies combining adequate protein intake with resistance training and structured behavioral support are recommended to improve the quality and durability of weight loss. Pharmacological approaches and novel agents that mitigate energy-expenditure reductions may enhance maintenance, but require long-term evaluation. Overall, sustainable weight loss is best conceptualized as a long-term process requiring alignment of physiology, behavior, and body composition rather than short-term restriction alone.