Losing weight isn’t just about eating less — for many, it’s about changing how the body responds to hunger and food.
That’s where Wegovy comes in.
It’s a prescription-only weight loss injection that’s now available privately and on the NHS (if you meet the criteria for eligibility), making it one of the most in-demand treatments in the UK.
But one key question remains: how long does Wegovy actually take to work?
Whether you’re just starting, waiting for results, or wondering if it’s doing anything at all, this article breaks down the full timeline of how Wegovy works, how fast you can lose weight, and what to expect at every stage.
Interested in weight loss treatment?
TL;DR: When does Wegovy start working?
Wegovy usually starts reducing appetite within 1 to 2 weeks, but visible weight loss typically begins after 4 to 8 weeks, especially once doses reach 1.0 mg and above.
Here’s a simplified overview:
- Weeks 1–4: Low-dose phase (0.25 mg) — limited weight loss, mild appetite change
- Weeks 5–8: 0.5 mg — hunger gradually reduces, early signs of fat loss
- Weeks 9–12: 1.0 mg — stronger satiety, improved food control, weight loss more noticeable
- Weeks 13–16: 1.7 mg+ — consistent fat loss, reduced food noise
- Week 17 onward: 2.4 mg (maintenance) — full therapeutic effect
By week 16, many people lose at least 5% of their starting body weight, especially when Wegovy is paired with dietary and lifestyle changes.
But this is just the summary. What follows is a full breakdown of the science behind Wegovy, the dose-response effects, and the timeline based on real clinical evidence.
How long does Wegovy take to work?
Wegovy doesn’t act instantly.
It works gradually over weeks, partly because the body needs time to adapt and partly because the dosage increases slowly to reduce side effects.
Appetite suppression typically begins around week 2 or 3, but real weight loss tends to start between weeks 4 and 8.
By week 12, most users have begun losing weight, especially after reaching doses of 1.0 mg or more.
What dose does Wegovy start working at?
You begin with 0.25 mg per week, but that dose is designed for tolerability, not fat loss.
| Weeks | Wegovy Dose |
|---|---|
| 1–4 | 0.25 mg |
| 5–8 | 0.5 mg |
| 9–12 | 1.0 mg |
| 13–16 | 1.7 mg |
| 17+ | 2.4 mg (target) |
Most users report noticeable appetite suppression and early fat loss around 1.0 mg, with 2.4 mg providing the most consistent long-term effect.
When does Wegovy suppress appetite?
Wegovy mimics a hormone called GLP-1, which affects the brain and gut.
These hormones are primarily responsible for:
- Slows stomach emptying
- Boosts satiety signals
- Reduces reward-driven eating
- Lowers food cravings between meals
This can start subtly at 0.5 mg, but stronger appetite suppression typically begins from 1.0 mg onwards.
What should I expect in week 1 of Wegovy?
Week 1 is about adjusting to the medication.
You might experience:
- Mild nausea or bloating
- A slight dip in hunger
- Headache or tiredness
- No major weight loss (normal)
This phase sets the foundation for tolerating higher doses without severe side effects.
How fast can you lose weight on Wegovy?
According to the STEP 1 and STEP 4 trials, average weight loss on Wegovy is:
| Time on Wegovy | Average Weight Loss (%) |
|---|---|
| 12 weeks | ~5% |
| 6 months | 10–12% |
| 68 weeks | 15–20% |
Real-world users in the UK often report:
- ½–1 stone lost within 2–3 months
- 1–2 stone over 6 months with lifestyle changes
Why is Wegovy not working yet?
Wegovy might feel ineffective in the early weeks if:
- You’re still on a low dose
- You’ve missed injections
- Diet and activity levels haven’t changed
- You’re metabolically resistant (e.g. PCOS, insulin resistance)
- Portion sizes are still too large
It typically takes until week 8 or later to see clear changes, especially after reaching 1.0 mg or more.
How long should you stay on Wegovy for weight loss?
Wegovy is licensed in the UK for long-term obesity management.
NICE recommends up to 2 years of use, with weight, side effects, and lifestyle regularly reviewed.
Discontinuing too soon can lead to weight regain, as Wegovy only works while active in the body.
What happens if there’s no weight loss by week 16?
NICE guidelines state that if less than 5% body weight is lost after 16 weeks on the full dose (2.4 mg), the treatment should be re-evaluated.
Doctors may:
- Stop Wegovy
- Explore alternatives (e.g. Mounjaro)
- Refer to dietitians or weight management services
This is a standard checkpoint to ensure continued clinical benefit.
How does Wegovy work scientifically?
Wegovy contains semaglutide, a GLP-1 receptor agonist. It targets multiple parts of the body to reduce hunger and promote fat loss:
- Stomach: Slows gastric emptying, so food stays in longer
- Pancreas: Increases insulin secretion post-meal
- Liver: Reduces glucagon, lowering fat storage
- Brain (hypothalamus): Activates satiety signals, reducing cravings
It doesn’t speed up metabolism — it lowers appetite and improves satiety, which indirectly leads to a calorie deficit and weight loss.
FAQs about Wegovy and its weight loss timeline
1. How long does it take Wegovy to suppress appetite?
Wegovy starts suppressing appetite between week 2 and week 4, depending on how quickly the dose increases. Stronger effects are seen at 1.0 mg and above.
2. When will I start losing weight on Wegovy?
Visible weight loss typically begins after 4 to 8 weeks, with stronger results from week 9 onwards. Most users see significant progress by week 12 to 16.
3. What if Wegovy isn’t working after 2 months?
If you’re still on a low dose (under 1.0 mg), that’s normal. If you’re at 1.7–2.4 mg and not seeing results, your doctor may review your diet and adherence or consider other causes. It would be better to speak with your prescriber or GP immediately.
4. Can Wegovy work faster if I eat better or exercise?
Yes. Combining Wegovy with calorie control, movement, and high-protein meals accelerates weight loss and improves long-term outcomes.
Research indicates that combining Wegovy with a calorie-restricted diet significantly enhances weight loss compared to using Wegovy alone.
5. Is it normal not to lose weight on 0.25 mg Wegovy?
Yes. The 0.25 mg dose is a starter dose, not a fat loss dose. It’s used for side effect control, not appetite suppression or weight loss.
6. How long should I stay on Wegovy?
In the UK, Wegovy is approved for use up to 2 years, with reviews every 6 months. Some patients continue beyond that based on results and medical need.