GLP-1 Receptor Agonists and Dual GIP/GLP-1 Receptor Agonists in Children and Adolescents with Obesity: Clinical Outcomes and the Impact of Nutritional and Behavioral Co-Interventions—A Systematic Review

Introduction: Glucagon-like peptide-1 receptor agonists (GLP-1 RAs), originally developed for the treatment of type 2 diabetes (T2D), are increasingly used for the management of overweight and obesity in children and adolescents. However, the impact of concomitant lifestyle interventions, which vary in scope, structure, and intensity, remains unclear. Methods: A systematic search of PubMed, Scopus, and ClinicalTrials.gov was conducted from April to December 2025 (last update: 12 December 2025), in accordance with the PRISMA 2020 statement. Randomized and observational studies including patients aged 6–19 years with overweight or obesity, with or without T2D, treated with GLP-1 RAs or dual GIP/GLP-1 agonists, were included. Anthropometric outcomes, metabolic parameters, and the scope and structure of concomitant nutritional and behavioral interventions were assessed. Results: Fifteen studies (12 interventional [RCT/non-RCT] and 3 observational), including 1448 participants, were analyzed: liraglutide (n = 6), exenatide (n = 5), semaglutide (n = 1), dulaglutide (n = 1), tirzepatide (n = 1), and lixisenatide (n = 1). Intervention duration ranged from 6 to 68 weeks. Reported BMI reductions varied across studies and pharmacological agents, with semaglutide trials reporting reductions of up to −16.1%. Lifestyle interventions were heterogeneously reported, ranging from general dietary advice to structured, multidisciplinary programs including nutritional counseling, physical activity, and behavioral or family support. Due to heterogeneity in study design and reporting, the independent contribution of lifestyle interventions could not be determined. Conclusions: Available evidence suggests that GLP-1 RAs may represent an effective therapeutic option for children and adolescents with obesity and metabolic disorders. However, available evidence is largely derived from studies incorporating inconsistently reported lifestyle interventions, limiting the ability to disentangle pharmacological and lifestyle effects. Standardized reporting and studies specifically designed to assess their independent and combined effects are needed. Future research should standardize the reporting of lifestyle protocols (e.g., using TIDieR), incorporate validated measures of eating behavior, food preferences, and dietary intake, and use designs (e.g., factorial or stratified randomization of lifestyle intensity) that allow for the pharmacological and behavioral contributions to be quantified separately. This review highlights a critical and previously underexplored methodological gap regarding the structure and reporting of lifestyle co-interventions in pediatric GLP-1 trials.