Morbid Obesity (Class III)
The most severe category of obesity, defined as BMI ≥40 or BMI ≥35 with serious weight-related comorbidities. Morbid obesity carries the highest risks of diabetes, cardiovascular disease, and premature death. Higher-dose GLP-1 receptor agonists and dual agonists show significant efficacy in this population.
Technical Context
BMI ≥40 (or ≥35 with severe comorbidities) carries the highest medical risk: 2-3× increased all-cause mortality, dramatically elevated rates of T2D (OR 5-12), cardiovascular disease, sleep apnoea (prevalence >50%), osteoarthritis, cancer (multiple types), depression, and reduced life expectancy by 8-14 years. Bariatric surgery has been the only effective treatment achieving durable >20% weight loss. GLP-1 RAs and dual agonists now produce weight losses in this range: semaglutide 2.4mg ~15% (STEP 1); tirzepatide 15mg ~22.5% (SURMOUNT-1). In patients with BMI ≥40, even larger percentage losses may be achievable with higher doses or combination approaches. Subgroup analyses from Phase III trials consistently show that patients with higher baseline BMI achieve similar or greater percentage weight loss, though they remain at higher absolute BMI post-treatment.