Effects of Ketogenic Diets on Body Composition in Adults with Obesity and Overweight – Systematic Review of Randomized Controlled Trials

Abstract

Effects of Ketogenic Diets on Body Composition in Adults with Obesity and Overweight – Systematic Review of Randomized Controlled Trials Abstract (250 words): Background/Objectives: Even though ketogenic diets (KD) are gaining more attention in weight management, their effects on body composition as a standalone treatment remain uncertain. The aim of this review was to evaluate the effects of KD (<50g/day of carbohydrate) as the sole intervention for over 12 weeks on body composition outcomes in adults living with overweight/obesity. Methods: Three different databases (Cochrane library, Embase, and Ovid Medline) were searched following PRISMA guidelines for randomized controlled trials (RCT’s) published in the last twenty years. Studies were included if they reported at least one of the following outcomes [fat mass (kg or %), lean mass (kg or %), fat-free mass “FFM” (kg), bone mass content (kg) or /density (g/cm2)]. Screening was performed using Rayyan website. Data were extracted and synthesized narratively exploring dietary composition heterogeneity, confirmation of ketosis, and data analyses. Risk of bias (RoB) was assessed using Cochrane RoB2 tool. Results: Eight studies met our criteria, all of them had concerns on risk of bias. Studies showed that KD had greater effects in decreasing body fat and lean mass compared to other interventions; however, these effects tend not to be significant. There were no effects on FFM and bone mass, but long-term studies were limited. Conclusions: KD appear to effectively decrease fat mass but may negatively affect lean mass especially in the short term. Future studies should aim for controlling carbohydrate and protein intake to confirm the impacts of KD on body composition in the long term.