DOI: https://doi.org/10.36347/sjams.2026.v14i08.003

Pages: 1099-1105

Background: Obesity is a chronic multifactorial disease associated with excess adiposity, metabolic dysfunction, and increased risk of cardiovascular and other obesity-related complications. Tirzepatide, a dual glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 receptor agonist, has emerged as an effective pharmacological treatment for obesity. However, assessment of its effects on body composition, including fat mass, lean mass, skeletal muscle, and body water compartments, is important for understanding the overall clinical impact of therapy. Objective: To evaluate the impact of tirzepatide therapy on body weight, BMI, body composition, and selected metabolic parameters among adults with overweight or obesity. Methods: This prospective observational study was conducted at the Department of Medicine, Tairunnessa Memorial Medical College, Gazipur, Bangladesh, from June 2024 to July 2025. A total of 45 adults with overweight or obesity who initiated once-weekly tirzepatide therapy were enrolled by consecutive sampling and followed prospectively. Baseline and follow-up assessments included body weight, BMI, body fat percentage, fat mass, fat-free mass, skeletal muscle mass, SMM-to-age index, dry lean mass, total body water, extracellular water, intracellular water, and ECW: TBW and ECW: ICW ratios. Tirzepatide was initiated at a low dose and gradually escalated according to clinical response and tolerability. Changes in body composition were evaluated overall and according to sex and initial BMI category. Results: The mean age of participants was 53 years. Following tirzepatide therapy, the proportion of participants with BMI ≥35 kg/m² decreased from 55.6% to 4.4%, while those with BMI <35 kg/m² increased from 44.4% to 95.6%. Body weight decreased by 28.2% and BMI by 27.9%. Body fat and fat mass declined by 37.6% and 54.2%, respectively, while fat-free mass, skeletal muscle mass, SMM-to-age index, and dry lean mass decreased by 7.3%, 8.2%, 8.3%,