Semaglutide Results: Average Weight Loss by Week
Quick Answer
Semaglutide (Wegovy 2.4 mg) produces a progressive, accumulating weight loss over 68 weeks: approximately 5% by week 12, 10% by week 20, and a final average of 14.9% at week 68. The fastest weekly weight loss rate typically occurs between weeks 16–28, once the full dose is established.
Week-by-Week Average Weight Loss Data
The STEP 1 trial published granular week-by-week weight loss data, allowing us to map the average trajectory precisely:
| Timepoint | Average % Weight Lost | Average lbs (220 lb start) |
|---|---|---|
| Week 4 | ~1.5% | ~3 lbs |
| Week 8 | ~3.5% | ~8 lbs |
| Week 12 | ~5.3% | ~12 lbs |
| Week 20 | ~8.4% | ~18 lbs |
| Week 28 | ~11.0% | ~24 lbs |
| Week 40 | ~13.0% | ~29 lbs |
| Week 52 | ~14.0% | ~31 lbs |
| Week 68 | ~14.9% | ~33 lbs |
Note: These are averages across all patients at the assigned maintenance dose (2.4 mg for the semaglutide group). Patients who are non-responders or who discontinued are included, which pulls averages slightly downward.
The Shape of the Weight Loss Curve
Semaglutide weight loss follows a characteristic pattern: slow start, accelerating middle, gradual plateau.
- Weeks 1–8: Minimal weight loss. Still at starting dose (0.25 mg → 0.5 mg). Appetite suppression is partial.
- Weeks 8–24: Fastest rate of weekly weight loss. Dose increasing through 1 mg → 1.7 mg → 2.4 mg. Full appetite suppression establishing.
- Weeks 24–52: Weight loss continues but decelerates. Full dose established; body adapting.
- Weeks 52–68: Plateau for most patients. Weight maintained or continuing to decrease slowly.
How Semaglutide Results Compare by Dose
| Dose | Average % Weight Loss |
|---|---|
| 0.25 mg (starting) | ~1–2% |
| 0.5 mg | ~3–5% |
| 1.0 mg | ~6–8% |
| 1.7 mg | ~10–12% |
| 2.4 mg (maintenance) | ~14.9% |
This dose-response relationship confirms that maximizing the dose, within tolerability limits, maximizes outcomes.
Distribution of Results
The average conceals substantial individual variation. In the STEP 1 trial at week 68:
- 14% of patients lost less than 5% (non-responders)
- 36% lost 5–15%
- 30% lost 15–20%
- 10% lost more than 20%
Roughly 1 in 3 patients loses between 15–20%; roughly 1 in 10 loses more than 20%.
Semaglutide Results in People With Type 2 Diabetes
Results are lower in people with type 2 diabetes:
- STEP 2 (diabetes population): -9.6% average at 68 weeks vs. -14.9% in non-diabetic population
- The mechanism behind this difference includes beta-cell dysfunction, different hormonal milieu, and the metabolic effects of diabetes medications
Long-Term Semaglutide Results
STEP 5 (104 weeks, 2 years):
- Semaglutide maintained -15.2% body weight at 2 years — comparable to the 68-week result
- Confirms that results are durable with continued treatment, not a flash-in-the-pan
The 2-year data is critical for anyone considering long-term use: the weight loss achieved at 12–18 months is maintained, not reversed, as long as the medication continues.
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Bottom Line
Semaglutide produces progressive weight loss that builds over 12–18 months. Don't judge results at week 4, 8, or even 12 — the most productive period is months 4–12 at the 2.4 mg maintenance dose. Final average: 14.9% at 68 weeks, maintained at 15.2% at 2 years.
Frequently Asked Questions
Sources
- Wilding JPH et al., "Once-Weekly Semaglutide in Adults with Overweight or Obesity," NEJM, 2021
- Ryan DH et al., "Long-term weight loss effects of semaglutide in obesity without diabetes," The Lancet, 2021
- Davies M et al., "Semaglutide 2·4 mg once a week in adults with overweight or obesity, and type 2 diabetes (STEP 2)," The Lancet, 2021
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