Yeast Protein Supplementation and Muscle Preservation During GLP-1RA-Induced Weight Loss

Inclusion Criteria: * Adults aged 25-50 years with overweight or obesity, defined as BMI ≥24.0 kg/m², who meet the clinical indication for GLP-1RA-related weight-loss treatment. Planning to initiate GLP-1RA treatment, or having initiated GLP-1RA treatment within the previous 4 weeks, and intending to continue treatment for at least 12 weeks. Able and willing to provide written informed consent and comply with the 12-week intervention, follow-up visits, dietary assessments, body composition measurements, muscle function tests, and biological sample collection. Exclusion Criteria: * Known allergy or intolerance to yeast protein, whey protein, milk-derived ingredients, or other components of the study products. Unable to undergo dual-energy X-ray absorptiometry (DXA) or having a contraindication to DXA examination. Sarcopenia at baseline, defined by appendicular skeletal muscle mass index (ASMI) \<7.0 kg/m² in men or \<5.4 kg/m² in women. Severe cardiovascular or cerebrovascular disease, hepatic or renal insufficiency, malignancy, or other diseases that may substantially affect skeletal muscle metabolism. Regular use of protein powder or additional protein supplementation equivalent to ≥0.3 g/kg body weight per day. Initiation or dose adjustment of statins within the previous 3 months, or a history of statin-associated myopathy. Current participation in another weight-loss program or clinical intervention trial. Long-term use of systemic glucocorticoids, anabolic agents, or other medications that may substantially affect protein or skeletal muscle metabolism. Use of other weight-loss medications, fat-loss supplements, or muscle-enhancing products within the previous 3 months, apart from the prespecified GLP-1RA-related treatment. Use of antibiotics, probiotics, prebiotics, or other products or medications likely to substantially affect the gut microbiota within the previous 1 month.