Discontinuation is the unresolved problem of the GLP-1 era. Trial-based 22-28% mean weight loss numbers assume sustained dosing — and real-world claims data show most patients are not on these drugs long enough to come close.
Covered here: the Prime Therapeutics commercial claims analysis (cited in May 2026 Managed Healthcare Executive) showing just 8.1% three-year persistence on anti-obesity medications; the Medicaid 6-month data showing ~61% on-treatment at six months; the Oxford post-discontinuation regain study from January 2026 (weight regain faster than diet-program discontinuation); the 0.8 kg/month average regain rate for semaglutide and tirzepatide; and the PBM-led persistence interventions — Optum Rx Weight Engage, Rightway Care Complete, MedImpact GLP-1 Benefit 360 — embedding multidisciplinary support to lift persistence above the current floor.
Stories here cover the claims-data analyses, the prescriber-side maintenance protocols, and the policy implications for coverage decisions. See #real-world-evidence, #glp-1, and #pbm-access.
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.
TRIUMPH-1's safety profile landed alongside the efficacy headline. Discontinuation rates due to adverse events were 4.1%, 6.9%, and 11.3% on retatrutide 4 mg, 9 mg, and 12 mg respectively, versus 4.9% on placebo. The most common adverse events were nausea, diarrhea, constipation, and vomiting — generally mild-to-moderate, concentrated during dose escalation, and decreasing over time. The hepatic-enzyme signal that appeared in TRIUMPH-4 (December 2025) reappeared as transient ALT elevations in a subset of participants on 9 mg and 12 mg dosing, normalizing by week 24. Liver fat dropped >80% on 8-12 mg dosing, supporting the interpretation that the transient transaminitis reflects hepatic triglyceride mobilization rather than hepatotoxicity. The 12 mg discontinuation rate at 11.3% sits modestly above tirzepatide 15 mg in SURMOUNT-1 (~7%) and Wegovy 2.4 mg in STEP 1 (~6.5%) — a tolerability gap that prescribers and patients will weigh against the efficacy gain.
An ECO 2026 analysis covered May 18 by ScienceDaily examined 89,718 patients starting GLP-1 therapy — 75.6% semaglutide, 17.5% tirzepatide, 6.9% liraglutide — and stratified BMI change at year one. In the first year, 27% reduced BMI by less than 5%, 22.4% by 5-10%, 14.1% by 10-15%, and 15.8% by ≥15%, while 20.8% actually gained weight. Greater weight loss correlated with larger reductions in obesity-related risk endpoints; patients who gained weight after starting treatment faced worse health outcomes than untreated comparators in several measures.
Real-world data presented in the ECO 2026 cycle counters the trial-based efficacy headlines: a Prime Therapeutics commercial claims analysis (cited in the May 2026 Managed Healthcare Executive cover story) found just 8.1% of members persisted with anti-obesity GLP-1 medications for three years. A separate 6-month Medicaid persistence analysis showed roughly 61% staying on treatment at six months. The high attrition is driven primarily by GI tolerability, insurance turnover, and out-of-pocket costs after step-edit programs. For newer agents like semaglutide and tirzepatide, post-discontinuation weight regain averages 0.8 kg per month — projecting return to baseline by ~1.5 years. PBM programs (Optum Rx Weight Engage, Rightway, MedImpact GLP-1 Benefit 360) are now embedding multidisciplinary support to lift persistence above the current floor.
An NPR investigation found fewer than 1 in 4 patients stay on GLP-1 medications after a year, with most planning to restart later. Researchers warn that up to 40% of weight lost on GLP-1s is lean muscle, and cycling on and off the drugs may accelerate sarcopenia. When patients stop, fat regains rapidly while muscle recovery is uncertain.
New research finds approximately 25% of weight lost persists after GLP-1 discontinuation. Trajectories were similar across semaglutide, liraglutide, and tirzepatide.