Preserving Lean Mass in Weight Loss Management

by: Samantha Pederson, PA-C

Lean muscle mass loss is a recognized consequence of weight loss induced by glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptor agonists. Clinical trials and meta-analyses indicate that approximately 20–40% of total weight lost with these agents is from lean body mass, including skeletal muscle. The proportion of muscle loss is influenced by the degree and rapidity of weight reduction, baseline nutritional status, age, and the presence or absence of structured resistance training. 

The American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society jointly recommend that all patients on GLP-1-based therapies undergo baseline assessment of muscle strength and body composition, and that structured resistance training be prescribed alongside pharmacotherapy to mitigate muscle loss. Resistance training, performed at least 2–3 times per week, is the most effective intervention to preserve muscle mass and function during weight loss.

Adequate dietary protein intake is essential. The Obesity Society recommends a target of 1.2–1.6 g/kg/day (actual or adjusted body weight) or 1.5 g/kg of lean body mass per day during active weight loss, with protein-rich foods prioritized at meals. However, protein supplementation alone is insufficient without concurrent resistance training.

Creatine and branched chain amino acids (BCAAs) may provide additional benefits. Supplementation with creatine (typically 3–5 g/day) and leucine (typically 2-3 g/day) has been shown to support muscle protein synthesis and may help preserve muscle mass, particularly when combined with resistance training, though robust data in the context of GLP-1/GIP therapy are limited. These adjuncts are generally considered safe and reasonable for patients at higher risk of sarcopenia or with difficulty meeting protein targets in the absence of kidney disease.

Summary:

-Titrate GLP and GIP medications slowly, with frequent visits to counsel patients

-Encourage adequate protein intake (1.2-1.6 g/kg/day)

-Encourage high repetition, low weight, compound exercises for resistance training at least 2-3 days per week for 30-45min per session

-Consider creatine and/or leucine supplementation in select patients