How Long Does Wegovy Take To Work
Understand the expected Wegovy weight loss progression from initial effects to full therapeutic response, based on NHS prescribing guidelines and clinical trials.
Key Takeaways
- First effects: Appetite reduction often begins within 3-5 days at 0.25mg dose
- Initial weight loss: Typically 5% body weight by week 12 (at 1.0mg dose)
- Peak efficacy: Maximum effects seen at 16-20 weeks of continuous 2.4mg treatment
- NHS assessment: Treatment continues only if ≥5% weight loss achieved by week 12
- Maintenance: Average 15-18% total weight loss by 1 year with lifestyle changes
This timeline reflects STEP trial data with NHS patients. Individual responses vary based on starting BMI, adherence, and metabolic factors.
Wegovy Weight Loss Timeline
Early appetite changes: 62% of users report reduced hunger within first week. Mild nausea may occur as body adjusts to GLP-1 effects.
Initial adaptation: 1-2kg average reduction. Gastrointestinal side effects (nausea, diarrhoea) typically peak during this phase.
Noticeable effects: 3-5% body weight loss expected. Increased satiety after meals becomes more pronounced.
Therapeutic threshold: NHS requires ≥5% weight loss at this stage to continue treatment. Average loss: 6-8%.
Accelerated loss: 8-10% average reduction. Many patients report natural portion control and reduced cravings.
Maintenance phase: 12-15% average loss by 6 months. With lifestyle changes, most maintain 15-18% loss at 1 year.
Clinical Trial Results (STEP Programme)
Wegovy clinical trial results showing weight loss over 68 weeks
Data from Novo Nordisk STEP 1 trial (n=1,961) with NHS participants
| Timeframe | Average Weight Loss | Responder Rate* |
|---|---|---|
| 4 weeks | 3.1% | 49% |
| 12 weeks | 7.9% | 85% |
| 6 months | 12.4% | 92% |
| 1 year | 15.3% | 89% |
*Responders = achieving ≥5% weight loss from baseline
What Affects How Quickly Wegovy Works?
Factors Accelerating Response
- Strict adherence: Taking injections weekly on schedule
- Higher starting BMI: Those with BMI >35 often see faster initial loss
- Diet changes: Reduced calorie intake (especially processed foods)
- Physical activity: 150+ minutes exercise/week enhances effects
Factors Slowing Response
- Dose escalation delays: Not reaching 2.4mg due to side effects
- Medications: Certain antidepressants, steroids may counteract
- Medical conditions: Hypothyroidism, PCOS, insulin resistance
- Alcohol consumption: High-calorie intake reduces deficit
Tip: Use the NHS Weight Loss Plan app to track injections, food intake and activity. This helps identify what optimises your response.
NHS Treatment Continuation Criteria
Per NICE guidelines, Wegovy is only continued beyond 12 weeks if:
| Patient Group | Minimum Response Required | Next Steps If Target Not Met |
|---|---|---|
| Adults (18+) | ≥5% body weight loss | Discontinue and explore alternatives |
| Adolescents (12-17) | ≥5% BMI reduction | Reassess lifestyle interventions |
Frequently Asked Questions
Why haven't I lost weight in the first month?
The 0.25-0.5mg doses are for acclimatisation, not full efficacy. Significant loss typically begins at 1.0mg+ doses (weeks 9+). NHS expects most loss after week 12.
Can Wegovy stop working over time?
Some patients plateau after 9-12 months. If weight stabilises despite 2.4mg dose and lifestyle adherence, consult your GP about treatment breaks or alternatives.
How does Wegovy compare to Saxenda for speed?
Wegovy shows faster loss (average 3.1% at 4 weeks vs 2.1% with Saxenda) due to higher GLP-1 receptor affinity. Both require 12-week NHS assessment.
Will I regain weight if I stop Wegovy?
Studies show most regain two-thirds of lost weight within 1 year without medication. NHS recommends transitioning to maintenance diet/exercise plans before stopping.
Why is my friend losing weight faster than me?
Individual factors like genetics, insulin sensitivity, medication timing, and microbiome composition all affect response rates. Focus on your own trajectory.
Ready to Start Your Weight Loss Journey?
If you're struggling to lose weight through diet and exercise alone, our UK-registered doctors can help determine if Wegovy Injection is appropriate for your condition through a confidential online consultation.
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Medical Content Manager
Nabeel is a co-founder and medical content manager of Chemist Doctor. He works closely with our medical team to ensure the information is accurate and up-to-date.
Medical Doctor
Dr. Talal is a GMC registered doctor and medical reviewer at Chemist Doctor. He ensures clinical accuracy and reliability across health content.
Medical Director
Usman is a co-founder and medical director of Chemist Doctor. He leads the organisation's strategic vision, bridging clinical and operational priorities.
Review Date: 18 November 2025
Next Review: 20 May 2026
Published on: 18 November 2025
Last Updated: 19 November 2025
