The typical timeline
| Timeframe | Dose | Expected weight loss | What's happening |
|---|---|---|---|
| Weeks 1–4 | 0.25mg | 0.5–1.5% | Starting dose. Appetite changes begin. Scale may barely move. |
| Weeks 5–8 | 0.5mg | 1–3% total | Weight loss becoming noticeable. Clothes may feel looser. |
| Weeks 9–16 | 1.0–1.7mg | 3–7% total | Significant loss. This is when people around you start to notice. |
| Weeks 17–40 | 2.4mg | 7–15% total | Maintenance dose. Most rapid loss period. Steady ongoing reduction. |
| Weeks 40–68 | 2.4mg | 12–17% total | Weight loss slowing and stabilising at maximum. |
| 68+ weeks | 2.4mg | ~15% maintained | Weight stable at new lower level while on medication. |
What the trials showed
In the STEP-1 trial (1,961 participants), the average weight loss trajectory was:
- Month 3: ~5% body weight lost
- Month 6: ~10% body weight lost
- Month 12: ~14% body weight lost
- Month 16 (week 68): ~14.9% body weight lost (maximum)
In practical terms, for someone starting at 100kg: ~5kg lost by month 3, ~10kg by month 6, ~15kg by month 16.
Why results vary
These are averages. In reality, results vary enormously:
- About one-third of participants lost 20%+ — the "super responders"
- About 86% lost at least 5% — clinically meaningful for most people
- About 14% lost less than 5% — the medication didn't work well for them
Factors that influence your response include genetics, starting BMI, diet quality, physical activity level, medication adherence, dose tolerance, sleep quality, and stress levels.
The first month is the hardest to judge
The biggest mistake people make is judging results during the first month. You're on the lowest dose (0.25mg) — it's intentionally sub-therapeutic. The real weight loss begins at month 3–4 when you reach higher doses. If you're barely losing weight in month 1, that's completely normal.
When to worry
If you haven't lost at least 5% of body weight after 6 months at the full maintenance dose (2.4mg), your doctor should reassess. Options include switching to Mounjaro (which works through a different mechanism and may succeed where semaglutide doesn't) or investigating other factors affecting weight loss.