Real-world effectiveness of 6-month tirzepatide therapy on body weight and composition in adults with overweight and obesity

AIMS/HYPOTHESIS: Obesity drives cardiometabolic dysfunction and increases cardiovascular risk, with excess fat mass and impaired body composition playing a key role in metabolic outcomes. This clinical study aimed to evaluate the real-world effectiveness (RWE) of tirzepatide on body weight, body composition, and metabolic parameters in adults with obesity or overweight and at least one obesity-associated comorbidity. METHODS: A 24-week retrospective observational analysis included 122 adults (80% women; mean age 44 ± 15 years) with overweight or obesity, and without diabetes. Participants received tirzepatide in combination with a standardized low-carbohydrate diet and tailored physical activity. Tirzepatide was initiated at a dose of 2.5 mg once weekly and increased to 5 mg after 4 weeks. Subsequent dose adjustments were individualized. Anthropometric measurements, bioelectrical impedance analysis and metabolic parameters were assessed at baseline and after 24 weeks. RESULTS: ) waist circumference (from 109 ± 16 to 92 ± 12 cm) and waist-to-height ratio (from 0.66 ± 0.1 to 0.56 ± 0.1), all p < 0.001. Fat mass (FM) largely reduced by 35%, fat-free mass slightly decreased by 5% (p < 0.001 for both), while skeletal muscle mass was preserved (p = ns). Metabolic parameters were also improved, including HbA1c (from 5.5 ± 0.4% to 5.2 ± 0.1%, p = 0.007), fasting plasma glucose (from 93 ± 12 to 84 ± 9 mg/dL, p < 0.001), fasting insulin (from 17 ± 15 to 12 ± 9 μIU/mL, p = 0.002) and HOMA-IR (from 4.2 ± 4.7 to 2.5 ± 2.1, p = 0.001). Correlation analysis revealed that the reduction in FM was significantly associated with the reduction in both insulin (r = 0.498, p < 0.05) and HOMA-IR (r = 0.513, p < 0.05). Interestingly, the weight loss found in our real-world cohort after 24 weeks of tirzepatide therapy (-16%) was identical to that found in the SURMOUNT-1 trial but after 72 weeks. CONCLUSIONS: In this RWE study, 24 weeks of tirzepatide treatment led to significant improvement on body weight, BMI and fat mass, together with preservation of lean skeletal muscle mass, as well as improved glycemic control and insulin sensitivity. Our findings suggest that a comprehensive clinical approach to obesity in real-world settings may be more beneficial than what observed in clinical trials.