Macronutrient, Micronutrient Supplementation and Monitoring for Patients on GLP-1 Agonists: Can We Learn from...

Background/Objectives: Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are increasingly prescribed for people living with obesity and type 2 diabetes due to their efficacy in reducing appetite and body weight. However, by inducing caloric restriction and altering gastrointestinal physiology, GLP-1RAs may predispose patients to nutritional deficiencies. This review aimed to synthesise current evidence on energy, protein, vitamin, and mineral status in GLP-1RA users, and contextualises these findings with metabolic and bariatric surgery (MBS) guidelines. While metabolic and bariatric surgery (MBS) guidelines mandate structured nutritional monitoring, no equivalent frameworks exist for GLP-1RA therapy, highlighting a critical gap that justifies the need for this review. Methods: A narrative review was conducted in three stages: (i) searching PubMed and Embase OVID (August 2025) using MeSH terms and free-text keywords related to GLP-1RAs, micronutrients, and obesity; (ii) screening abstracts and full texts for eligibility; and (iii) synthesising results with comparison to bariatric surgery protocols. Eligible studies included clinical trials, observational cohorts, and reviews reporting nutritional outcomes in GLP-1RA users or describing MBS monitoring guidelines. Results: GLP-1RA therapy consistently reduced caloric intake, with frequent inadequacy of protein intake and occasional sarcopenia. Observational data reported that users developed nutritional deficiencies within 12 months, most commonly vitamin D, followed by thiamine and other B vitamins. Mineral deficiencies, particularly in iron, calcium, magnesium, and potassium, were also observed. Conclusions: GLP-1RAs are associated with clinically relevant risks of protein, vitamin, and mineral deficiencies. The absence of formal monitoring protocols represents an unmet clinical need, and adaptation of surveillance, as seen in MBS, which may help mitigate long-term complications.