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
Free tracker included with every download this week
Is Wegovy Any Good? What the Evidence Shows
Yes, Wegovy can be effective for weight loss in the UK, but whether it's right for you depends on your individual health profile, eligibility, and NHS or private access. Clinical trials showed that semaglutide (the active ingredient in Wegovy) helped participants lose an average of around 15% of their body weight over 68 weeks when used alongside diet and exercise changes. However, results vary significantly between individuals, and it's prescription-only, so you'll need a clinical assessment from a GP or registered prescriber to determine suitability. This guide explains NHS eligibility, NICE guidance, real-world effectiveness, and how Wegovy compares to alternatives like Mounjaro.
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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.
Wegovy Effectiveness: What NICE and NHS Guidance Says
NICE (National Institute for Health and Care Excellence) has recommended semaglutide as an option for weight management in UK adults who meet specific eligibility criteria. NICE's 2021 guidance supports GLP-1 receptor agonists like Wegovy for use within NHS specialist weight management services, though access varies significantly by region.
In the STEP-1 clinical trial, adults receiving the maximum Wegovy dose (2.4 mg once weekly) lost an average of 14.9% of their body weight at 68 weeks, compared to around 2.7% with a placebo. Participants also typically lost about 3–4 kg more than those on diet and exercise alone. However, this was achieved alongside a structured reduced-calorie diet and increased physical activity—Wegovy is not a standalone solution.
Real-world UK experience shows mixed results. Some patients experience significant weight loss (15–20%+), others see modest results (5–10%), and approximately 1 in 4 people stop because of side effects, primarily nausea. Individual factors like baseline weight, metabolism, adherence, and lifestyle changes greatly influence outcomes. Use our free GLP-1 weight loss calculator to estimate potential weight loss at different doses based on current evidence.
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.
NHS vs Private Access: Getting Wegovy in the UK
NHS route: Wegovy is available through NHS tier 3 specialist weight management services, but only by referral from your GP. You'll need a BMI of 30 or above (or 27+ with weight-related health conditions like type 2 diabetes, hypertension, or heart disease). Waiting lists can be very long in many areas—months to over a year in some regions. Check your local Integrated Care Board (ICB) for availability.
Private route: Available through UK-licensed online prescribers following a clinical consultation. No NHS waiting list required, but you'll pay per dose (typically £130–£250/month). Private prescribers assess the same eligibility criteria as NHS services.
Either way, use our BMI calculator above to check if you meet the BMI threshold, and discuss your options with your GP or a registered prescriber to decide the best route for you.
- 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.
How does Wegovy compare to Mounjaro for weight loss?
Both are once-weekly injections for weight loss in the UK. Wegovy (semaglutide, GLP-1 agonist) showed average weight loss of ~15% in trials. Mounjaro (tirzepatide, dual GIP+GLP-1 agonist) showed ~15–21% in SURMOUNT trials. Mounjaro may offer slightly greater weight loss on average, but individual results vary. Your prescriber will recommend based on your health profile and eligibility.
What are the main side effects of Wegovy?
Most common are nausea, diarrhoea, vomiting, and constipation—especially when starting or increasing doses. These often improve over time. Rare serious side effects include pancreatitis and gallbladder issues. Side effect severity varies greatly. Your GP should discuss all risks before prescribing, and report any concerns immediately.
Can I get Wegovy on the NHS?
Yes, through NHS tier 3 specialist weight management services if you meet eligibility criteria (BMI ≥30, or ≥27 with weight-related health conditions). Access varies by region and waiting lists are often long. Ask your GP about referral to your local specialist service, or explore private prescribing for faster access.
How long do you stay on Wegovy?
Treatment duration varies. Some people use it for 6–12 months to reach their goal weight, then stop under medical supervision. Others use it longer-term for weight maintenance. NICE guidance suggests reassessing regularly with your healthcare provider. Stopping without lifestyle support often results in weight regain.
Is semaglutide the same as Wegovy?
Semaglutide is the active ingredient in Wegovy. Ozempic also contains semaglutide but is licensed for type 2 diabetes (not weight loss in the UK). Wegovy is the licensed weight management version at higher doses (up to 2.4 mg weekly). Only Wegovy should be used for weight loss in the UK.
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.