Percentage Weight Loss
Weight reduction expressed as a percentage of starting body weight — the standard primary efficacy measure in obesity clinical trials. A 5% weight loss threshold is considered clinically meaningful. Semaglutide 2.4mg produced approximately 15% mean weight loss; tirzepatide demonstrated up to 22.5%.
Technical Context
Clinical significance thresholds: ≥5% weight loss produces meaningful improvements in metabolic risk factors (HbA1c, blood pressure, lipids, sleep apnoea); ≥10% produces significant cardiovascular risk reduction and potential diabetes remission; ≥15% approaches bariatric surgery-level metabolic benefits. GLP-1 RA efficacy: liraglutide 3.0mg ~8%, semaglutide 2.4mg ~15%, tirzepatide 15mg ~22.5% (all placebo-adjusted at 68-72 weeks). Responder analysis: percentage achieving ≥5%/≥10%/≥15%/≥20% thresholds provides clinically meaningful context beyond mean weight loss. For semaglutide 2.4mg: ~86% achieve ≥5%, ~70% achieve ≥10%, ~50% achieve ≥15%, ~32% achieve ≥20%. Individual variability is significant — genetic, behavioural, and microbiome factors likely contribute to differential response.