Impact of Diet Interventions for Weight Loss on Lean Body Mass and Resting Metabolic Rate: A Systematic Review

Individuals with excess weight are at a higher risk of overall health issues and often seek to modify their diets to lose weight. Weight loss can alter body composition, leading to a decrease in lean body mass (LBM) and resting metabolic rate (RMR). Limited research has examined the relationship between different dietary modifications and body weight, LBM, and RMR.

This review aimed to research the impact of weight-loss dietary interventions on body weight, LBM, and RMR in adults with overweight or obesity.

The search was conducted using the following databases: CINAHL, Cochrane Library, Embase, PubMed, Scopus, Web of Science, Google Scholar, and Dissertations & Theses Global.

The initial search found 8838 studies. The title and abstract screening identified 138 studies for full-text review. As a result, 16 studies were selected for this systematic review. The studies had to be original, published in English over the last 10 years, and include adults as participants. The intervention had to be any weight-loss dietary modification, and the outcomes had to include measurements of body weight, LBM, and RMR.

The included intervention groups implemented the following dietary modifications: altering calorie intake, macronutrient composition, and meal timing. Across all studies, the dietary interventions resulted in all participants losing a substantial amount of weight. Changes in LBM and RMR, however, were not as consistent across the groups, but there was an overall downward trend. Physical activity did not confound the outcomes of the included studies.

Regardless of the type of dietary modification and inclusion of physical activity, any change in diet resulted in significant weight loss. Changes in LBM and RMR varied, with a tendency to decrease. Future studies should research the long-term effects of diet interventions on the outcomes of interest.

PROSPERO registration no. CRD420251074910/.