Patients starting GLP-1 therapy often ask the same question: "When will I see results?" The answer varies, but clinical trial data gives us a realistic timeline. This article walks through what to expect at each stage, based on the STEP (Wegovy) and SURMOUNT (Zepbound/Mounjaro) clinical trial datasets.
Weeks 1-4: Onboarding
Most prescribers start GLP-1 at a low dose (0.25mg Wegovy / 2.5mg Zepbound) and titrate up monthly. Early weight loss in this phase is typically modest — 2-5 lbs is common. The primary purpose of this phase is tolerance, not rapid weight loss.
- Expect mild appetite reduction within 1-2 weeks
- Common side effects: nausea, mild GI upset (usually resolve within 1-2 weeks)
- Average weight loss week 4: ~2.5 lbs
Weeks 4-12: Steady progress
Dose typically increases over weeks 4-12. Appetite suppression and reduced food noise become more pronounced. Weight loss accelerates.
- Average cumulative loss by week 12: ~5-7% of starting body weight
- For a 200 lb person, ~10-14 lbs
- Side effects often stabilize or improve
- Many patients report needing significantly smaller portions
Weeks 12-24: Approaching maintenance dose
By week 16-20, most patients have reached or are approaching the target maintenance dose (2.4mg Wegovy, 15mg Zepbound for those who tolerate). This is where weight loss is fastest for most.
- Average cumulative loss by week 24: ~10-12% (Wegovy), ~12-15% (Zepbound)
- For a 200 lb person, ~20-30 lbs
- Energy levels often improve
- Cardiovascular markers (blood pressure, lipids) typically improve in parallel
Weeks 24-48: Plateau and stabilization
Weight loss continues but at a slower rate. The body adapts metabolically; this is normal physiology.