The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
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Average Weight Loss On Wegovy — UK Data & Clinical Evidence
Wegovy (semaglutide) clinical trials showed an average weight loss of approximately 14.9% of body weight over 68 weeks in UK adults. However, individual results vary significantly based on dose, lifestyle changes, and personal factors. This guide explains the clinical data, how it translates to real kg and stone weight loss, and the factors that influence whether you'll achieve results at the higher or lower end of the scale. For context, our GLP-1 weight loss calculator can help you estimate potential outcomes at different doses based on your starting weight.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
Clinical Trial Data: What Wegovy Users Lost On Average
The main clinical evidence for Wegovy comes from the STEP-1 trial, which tracked adults taking semaglutide 2.4 mg (the maximum dose) over 68 weeks alongside a reduced-calorie diet and increased physical activity.
- Average weight loss: 14.9% of body weight at the full 2.4 mg dose
- Placebo comparison: The placebo group lost approximately 2.6% of body weight, so Wegovy's effect represents an additional ~12% loss beyond dietary changes alone
- Real-world examples: A UK adult weighing 100 kg would lose approximately 14.9 kg on average (15 kg). Someone at 80 kg might lose approximately 12 kg. Someone at 70 kg might lose approximately 10.4 kg
- In UK measurements: 14.9 kg equals approximately 2 stone 5 lbs on average
- Timeline: Maximum weight loss typically occurs at weeks 52–68, after reaching the full 2.4 mg dose
These are clinical trial averages. In practice, some people lose more (up to 20%), whilst others lose less (8–10%). Individual results depend on adherence, lifestyle factors, and personal response to the medication.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Factors That Influence Your Individual Weight Loss On Wegovy
Your actual weight loss on Wegovy depends on several factors beyond the medication itself. Calorie intake and diet quality are critical—Wegovy works alongside dietary changes, not instead of them. Physical activity level affects both the rate and sustainability of weight loss. Starting weight and metabolism play a role; people starting at a higher weight may lose more kg but a similar percentage. Age, genetics, and ethnicity influence metabolic rate and medication response. Dose and duration matter—those reaching the full 2.4 mg dose and staying on it longer tend to lose more. Baseline health conditions like type 2 diabetes or PCOS can affect outcomes. Our healthy weight calculator can show your target weight range—actual loss needed depends on your starting point and individual health goals.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Is clinically studied weight loss typical for everyone on Wegovy?
No. The 14.9% figure is an average from clinical trials. In reality, individual results range from approximately 8% to clinically studied weight loss. Your personal result depends on adherence to the medication, dietary changes, physical activity, genetics, starting weight, and how long you take it. Some people respond better than others.
How much weight would a typical UK adult lose on Wegovy?
It varies widely. An average UK adult woman (approximately 71.6 kg) might lose 10–11 kg on average (about 1 stone 8 lbs). An average UK adult man (approximately 85.7 kg) might lose 12–13 kg on average (about 2 stone). These are approximate figures—your actual loss depends on the factors mentioned above.
Does weight loss on Wegovy continue after stopping the medication?
Not typically. Clinical data shows most weight is regained if the medication is stopped without maintaining the dietary and lifestyle changes that supported the initial loss. This is why Wegovy is considered a long-term treatment—ongoing use supports ongoing weight management.
Why did some people in the trial lose more or less than 14.9%?
Clinical trial participants represent a range of responses. Factors like genetic variation, adherence to the reduced-calorie diet, exercise consistency, age, baseline metabolic rate, and individual medication sensitivity all influence outcomes. Some people naturally respond better to GLP-1 medications than others.
How does Wegovy weight loss compare to ideal body weight targets?
The STEP trial's average 14.9% loss may or may not be enough to reach a healthy BMI, depending on your starting weight and height. Use our BMI calculator to check your healthy weight range for your height. Your GP can discuss whether your target weight aligns with your individual health needs.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.