Rapid Weight Loss vs. Slow Weight Loss: Which is More Effective on Body Composition and Metabolic Risk Factors?

Background Achieving weight loss (WL) in a short time regardless of its consequences has always been the focus of many obese and overweight people. In this study, anthropometric and metabolic effects of two diets for rapid and slow WL and their consequences were examined. Methods Forty-two obese and overweight individuals were randomly divided to 2 groups; rapid WL (weight loss of at least 5% in 5 weeks) and slow WL (weight loss of at least 5% in 15 weeks). To compare the effects of the rate of WL in 2 groups, the same amount of was achieved with different durations. Anthropometric indices, lipid, and glycemic profiles, and systolic and diastolic blood pressures were evaluated before and after the intervention. Results Both protocols of rapid WL and slow WL caused reduction in waist circumference, hip circumference, total body water, body fat mass, lean body mass, and resting metabolic rate (RMR). Further reduction in waist circumference, hip circumference, fat mass, and percentage of body fat was observed in slow WL and decreased total body water, lean body mass, fat free mass, and RMR was observed in rapid WL. Improvement in lipid and glycemic profiles was observed in both groups. Reduction of low-density lipoprotein and fasting blood sugar, improvement of insulin resistance, and sensitivity were more significant in rapid WL in comparison to slow WL. Conclusions Weight Loss regardless of its severity could improve anthropometric indicators, although body composition is more favorable following a slow WL. Both diets improved lipid and glycemic profiles. In this context, rapid WL was more effective. (IRCT2016010424699N2).