Effectiveness of Combined GLP-1/GIP Dual Agonist Therapy and Structured Exercise on Skeletal Muscle Morphology, Quality, and Physical Function in Overweight and Obese Individuals

Effectiveness of Combined GLP-1/GIP Dual Agonist Therapy and Structured Exercise on Skeletal Muscle Morphology, Quality, and Physical Function in Overweight and Obese Individuals: a Randomized Controlled Trial Protocol

This randomized controlled trial aims to investigate the effects of a 24-week home-based progressive resistance exercise program combined with tirzepatide treatment on skeletal muscle mass, muscle quality, and functional capacity in overweight and obese individuals. A total of 108 participants initiating tirzepatide therapy will be randomized to either exercise plus pharmacotherapy or pharmacotherapy alone. The primary outcome is change in thigh muscle thickness and echo intensity assessed by ultrasonography.

Pharmacologically induced weight loss with glucagon-like peptide-1 (GLP-1)/ glucose-dependent insulinotropic polypeptide (GIP) receptor agonists such as tirzepatide is associated with significant reductions in lean body mass, raising concerns regarding muscle function and long-term outcomes. Resistance exercise is the most effective intervention to preserve muscle mass during weight loss; however, evidence combining these approaches is limited.

This study is a prospective, two-center, single-blinded, randomized controlled trial designed to evaluate whether structured resistance exercise enhances muscle preservation and functional outcomes in individuals receiving tirzepatide therapy.

Inclusion Criteria:

• initiation of tirzepatide-based pharmacological treatment as prescribed by an endocrinology and metabolism specialist,
• body mass index (BMI) ≥27 kg/m² and the presence of a comorbidity condition or BMI≥30 kg/m²
• age between 18 and 65 years

Exclusion Criteria:

• diagnosis of type 1 or type 2 diabetes mellitus
• presence of cerebrovascular, hematological, pulmonary, rheumatological, or neurological disorders
• current participation in a structured diet or exercise program
• use of weight-loss medications within the past 12 months
• history of upper or lower extremity surgery or injury within the past 6 months
• any contraindication to resistance exercise as determined by the treating physician.