Real-World Evidence for Wegovy (Semaglutide 2.4 mg Once Weekly Subcutaneous Injection) Documents 5.9% to 12% Mean Body Weight Reduction at 6 to 12 Months Across Registry and Claims Analyses, Compared to 14.9% Weight Loss in the STEP-1 Registrational Trial; The Gap Is Adherence-Driven With Missed Doses, Titration Pauses, and Stop-Restart Cycles Flattening Real-World Curves Relative to the Tight-Adherence STEP-1 Population; Cleveland Clinic Research Confirmed That Injectable Obesity Medications Produce Smaller Weight Loss in a Real-World Setting Compared to Randomized Clinical Trials; A Large Real-World Study of Nearly 8,000 Patients Found That Most People Who Discontinue GLP-1 Therapy Manage to Keep the Weight Off or Continue Losing by Restarting Treatment, Switching Medications, or Adopting Lifestyle Changes
Real-world evidence for Wegovy (semaglutide 2.4 mg once weekly subcutaneous injection) documents 5.9% to 12% mean body weight reduction at 6 to 12 months across registry and claims analyses. This compares to 14.9% weight loss in the STEP-1 registrational trial that supported the FDA approval. The gap is primarily adherence-driven: missed doses, titration pauses, insurance-driven dose changes, and stop-restart cycles flatten real-world curves relative to the tight-adherence STEP-1 population. Cleveland Clinic research confirmed that injectable obesity medications produce smaller weight loss in a real-world setting compared to randomized clinical trials, with the gap larger in patient subgroups facing financial barriers to consistent supply. A large real-world study of nearly 8,000 patients who discontinued GLP-1 therapy found that most manage to keep the weight off or continue losing by restarting treatment, switching medications (typically to tirzepatide or higher-dose Wegovy), or adopting lifestyle changes. Patient satisfaction is driven primarily by perceived effectiveness rather than tolerability: effective weight loss even with gastrointestinal side effects is associated with continued treatment adherence, while lower-efficacy responses lead to early discontinuation regardless of tolerability. The real-world evidence has implications for retatrutide's likely commercial trajectory: the 28.7% Phase 3 ceiling may translate to 15-20% in real-world use depending on adherence patterns, which is still substantially above semaglutide's real-world 5.9-12% range.