PP318 - EFFECT OF BRANCHED-CHAIN AMINO ACID SUPPLEMENTATION ON LEAN MASS PRESERVATION IN OBESE PATIENTS TREATED WITH TIRZEPATIDE: A 4-MONTH GCP OBSERVATIONAL STUDY

PP318

EFFECT OF BRANCHED-CHAIN AMINO ACID SUPPLEMENTATION ON LEAN MASS PRESERVATION IN OBESE PATIENTS TREATED WITH TIRZEPATIDE: A 4-MONTH GCP OBSERVATIONAL STUDY

B. Lucchetti¹, M. Mengani¹, G. M. Casuale¹, G. Baldoni¹, E. Regni¹, S. Toderi¹, D. Fumelli^1,*

¹UOSD Servizio di Dietetica e Nutrizione Clinica, Carlo Urbani Hospital, Jesi (AN), Ancona, Italy

Rationale: Dual GIP/GLP-1 receptor agonists such as tirzepatide are highly effective for obesity treatment but may lead to a reduction in lean body mass, potentially affecting muscle function and metabolic stability. Strategies such as branched-chain amino acid (BCAA) supplementation may support protein synthesis and help preserve muscle mass during pharmacologically induced weight loss.

Methods: A total of 67 obese patients were evaluated in 2025 at the UOSD Servizio di Dietetica e Nutrizione Clinica, Carlo Urbani Hospital, Jesi (AN), AST Ancona (Italy). All patients received tirzepatide (non-reimbursable) in combination with a personalized hypocaloric diet providing an average energy deficit of 500 kcal/day, along with structured physical activity (aerobic and resistance training).
Body composition was assessed by bioimpedance analysis (InBody S10) at baseline and after 4 months. Patients with a skeletal muscle index (SMI) < 5.7 kg/m² in women or < 7.0 kg/m² in men were prescribed, in accordance with Good Clinical Practice (GCP), oral BCAA supplementation at a dose of 5 g/day (4:1:1 leucine:isoleucine:valine). Mean changes were compared between groups (tirzepatide alone vs tirzepatide plus BCAA).

Results: After 4 months, mean weight loss was 9.8 ± 2.4%. Lean mass decreased by 7.6 ± 2.0% (ΔSMI = –0.54 ± 0.22 kg/m²) in patients receiving tirzepatide alone (n = 44), and by 4.0 ± 1.5% (ΔSMI = –0.25 ± 0.17 kg/m²; p < 0.05) in those also receiving BCAA supplementation (n = 23). 

Conclusion: Among obese patients treated with tirzepatide under controlled dietary and exercise conditions, BCAA supplementation (5 g/day, 4:1:1) was associated with a significantly lower reduction in lean mass. Targeted amino acid supplementation may represent a useful adjunct strategy for preserving muscle mass during pharmacological obesity treatment.

Disclosure of Interest: None declared