GLP-1 Peptide Therapy & Lean Mass Preservation: Key Nutrition Findings (2026)

Key Takeaways

• Fat mass loss predominates, but lean mass loss is clinically significant. Randomized trials with body-composition substudies confirm that while GLP-1RAs primarily reduce fat mass, a measurable and relevant reduction in absolute lean mass also occurs.
• Protein targets are higher than most patients consume. The review recommends a minimum of ≥1.2 g of protein per kg of body weight per day, with intakes up to 1.6 g/kg/day appropriate for most adults without CKD. Per-meal targets of 0.3–0.4 g/kg and a leucine dose of ~2.5–3 g per meal are proposed to maximally stimulate muscle protein synthesis.
• Micronutrient deficiencies are common at baseline and worsen during therapy. Reduced appetite, nausea, and vomiting associated with GLP-1RAs can compound pre-existing nutrient gaps common in individuals with obesity. The author recommends a structured laboratory panel including vitamin D, B12, iron studies, folate, zinc, and thiamine (especially in high-risk patients).