Dietary Strategies and Nutritional Management in Patients Receiving GLP-1 and Dual GIP/GLP-1 Receptor Agonists as Adjuncts to Lifestyle Interventions: A Systematic Review of Randomised Clinical Trials.

BACKGROUND: Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) and dual GIP/GLP-1 RAs are widely used to manage obesity, prediabetes and type 2 diabetes, typically in combination with lifestyle interventions. Their nutritional implications, however, remain unclear. This systematic review summarised evidence from randomised clinical trials investigating dietary strategies and nutritional management in individuals treated with these medications. METHODS: The review followed PRISMA guidelines and was registered in PROSPERO (CRD420251181076). Searches were conducted in PubMed, Embase, Scopus and Web of Science. Eligible studies were randomised clinical trials evaluating adults receiving GLP-1 or dual GIP/GLP-1 agonists in conjunction with lifestyle or dietary guidance. Outcomes included gastrointestinal symptoms, muscle and bone health and nutritional adequacy. RESULTS: Sixteen trials involving 7096 participants were included. GLP-1 and dual agonists consistently increased gastrointestinal symptoms such as nausea, diarrhoea, constipation and vomiting. These effects were often dose-related and occurred despite background lifestyle or dietary interventions. Lean mass was generally preserved, with reductions proportional to overall weight loss. No study directly assessed bone health, and none reported clinically relevant nutritional deficiencies. Most trials presented a low risk of bias. CONCLUSION: GLP-1 and dual GIP/GLP-1 agonists frequently cause gastrointestinal discomfort but tend to preserve lean mass during weight loss when used alongside lifestyle interventions. Although dietary guidance is commonly provided, evidence on optimal nutritional approaches remains limited. Further trials are needed to clarify protein requirements, assess musculoskeletal outcomes and establish evidence-based dietary recommendations to support combined treatment strategies.