What the withdrawal trials show
STEP-4 (semaglutide) and SURMOUNT-4 (tirzepatide) both addressed the same question: what happens when patients who reach a substantial weight loss withdraw from GLP-1 therapy?
In STEP-4, patients who completed a 20-week run-in losing a mean 10.6% of body weight were randomized to continue semaglutide or switch to placebo. Over the next 48 weeks, the continuation group lost an additional 7.9% on average; the placebo group regained 6.9%. Roughly two-thirds of the weight lost during the run-in was regained after withdrawal.
SURMOUNT-4 produced similar results for tirzepatide, with continued therapy adding modest further loss and placebo switch producing a regain of approximately 14 percentage points of body weight.
The clinical implication
GLP-1 therapy for obesity is, like most therapies for chronic conditions, best understood as a long-term intervention rather than a short course. The metabolic adaptations that follow weight loss — reduced leptin, increased ghrelin, lowered resting energy expenditure — push the body back toward its prior set point in the absence of ongoing pharmacologic support.
This is not a failure of the patient, the drug, or the discipline framework. It is a consistent feature of obesity physiology that the trials make unusually clear.
Maintenance dosing strategies
Several maintenance patterns are in clinical use, though none have head-to-head outcomes data:
• Continuation at the same effective dose indefinitely • Step-down to the next-lower dose once goal weight is achieved • Extended interval dosing (e.g., every 10–14 days instead of weekly) in selected patients
The step-down approach is most common in clinical practice and is supported by the SURMOUNT-4 design (which compared continuation vs withdrawal, not step-down). The intensity of any maintenance regimen should be calibrated to the individual patient's regain trajectory.
Cost planning for the long term
If maintenance is the realistic expectation, the cost-over-time calculation differs meaningfully from a short-course framing. At $189/month compounded tirzepatide, ten years of maintenance is roughly $22,700; at $1,000/month brand-name pricing, it's $120,000.
This is part of why pharmacy traceability and pricing-transparency disclosure matter so much at provider selection — you're making a multi-year decision, not a one-year one.