Abstract
BACKGROUND AND AIMS: Weight loss without adequate anabolic stimuli can lead to reductions in lean, as well as adipose, tissue. Health benefits typically associated with weight loss are therefore attenuated, as body composition potentially shifts from an obese to sarcopenic/frail phenotype. In contrast to the traditional connotation of frailty, this might occur in younger adults and is characterized by reduced performance in functional tasks of daily living. Nutritional supplements as an adjunct to weight loss intervention could support the maintenance of lean mass, particularly if structured exercise is contraindicated. This systematic review aims to quantify the effect of nutritional supplements, without concurrent exercise, on lean mass in individuals undergoing pharmacological and nonpharmacological-induced weight loss. METHODS: This protocol describes a prospective systematic review and meta-analysis of randomized controlled trials investigating the effect of nutritional supplements on lean mass during weight loss. Comparison arms will not use nutritional supplements. Literature searches will be conducted using the following online databases: Embase, MEDLINE, Web of Science, Google Scholar, and OpenGrey. Outcome measures related to body composition, lean mass, skeletal muscle mass/size, or physical function will be extracted. Risk of bias will be assessed using the United States National Heart Lung and Blood Institute quality assessment tool for controlled intervention studies. A meta-analysis will be conducted to synthesize comparable outcomes. RESULTS: The results of this review will be reported in adherence to PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols) standards, and published in a peer-reviewed journal. CONCLUSION: This study will be the first to systematically review nutritional interventions for the preservation or accretion of lean mass during weight loss. This review will identify gaps in the literature and inform the development of optimized weight loss strategies, for use in research and practice. TRIAL REGISTRATION: International Prospective Register of Systematic Reviews: PROSPERO CRD42024521540.