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
Does Metamorphine Cause Weight Loss?
Metamorphine (semaglutide) is a prescription-only weight loss medication that may help support weight management in UK adults. It's the active ingredient in Wegovy, a once-weekly injection licensed for weight management by the MHRA. While it's not a clinically studied weight loss solution, clinical trials have shown that, alongside a reduced-calorie diet and increased physical activity, it may help people lose weight. This guide explains how metamorphine works, what the evidence shows, and how to access it in the UK through NHS weight loss services or private prescription.
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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.
How Metamorphine Works for Weight Loss
Metamorphine is a GLP-1 receptor agonist — it mimics a natural hormone your gut produces after eating. This hormone signals to your brain that you're full, which may help reduce appetite and food cravings.
In the STEP-1 clinical trial, participants taking metamorphine (Wegovy) lost an average of around 15% of their body weight over 68 weeks, alongside lifestyle changes. However, individual results vary significantly — some people lose more, some lose less.
Key effects include:
- Reduced appetite and food cravings
- Feeling fuller after smaller meals
- Slowed stomach emptying (helps you feel satisfied longer)
- Better blood sugar control
Metamorphine is prescription-only and requires a clinical assessment before being prescribed. It's not suitable for everyone — your GP or a licensed prescriber will assess whether it's appropriate for you based on your individual health.
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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.
UK Eligibility and How to Access Metamorphine
In the UK, metamorphine (Wegovy) may be prescribed for adults with a BMI of 30 or above, or BMI of 27–29.9 with a weight-related health condition such as type 2 diabetes, high blood pressure, or cardiovascular disease. For South Asian, Chinese, Black African, and Black Caribbean adults, lower BMI thresholds apply due to higher health risks at lower weights.
NHS access: Referral to a tier 3 specialist weight management service through your GP. Availability varies by region and waiting lists can be long.
Private access: Online consultation with a UK-licensed prescriber through GPhC-registered pharmacies, available without NHS referral.
Use our free BMI calculator above to check if you may be eligible, and our GLP-1 weight loss calculator to estimate potential weight loss at different doses.
- 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 metamorphine the same as metformin?
No. Metamorphine is semaglutide (the active ingredient in Wegovy), a GLP-1 injection. Metformin is an oral tablet for type 2 diabetes. They are completely different medications with different mechanisms. Metamorphine is licensed for weight management; metformin is not.
How much weight can I lose on metamorphine?
Clinical trials show an average of clinically studied weight loss, but individual results vary. Some people lose more, some lose less. Weight loss depends on dose, adherence, diet, and physical activity. Always discuss realistic expectations with your prescriber.
Is metamorphine (Wegovy) the same as Ozempic?
Both contain semaglutide, but they are different medicines. Ozempic is approved for type 2 diabetes (up to 2mg). Wegovy is the licensed weight management version (up to 2.4mg). Using Ozempic for weight loss is off-label in the UK — Wegovy is the correct licensed option.
Can my GP prescribe metamorphine for weight loss on the NHS?
Not typically. Metamorphine is usually prescribed through NHS tier 3 specialist weight management services, not standard GP prescription. You'll need a referral from your GP. Availability varies significantly by region.
What are the side effects of metamorphine (Wegovy)?
Common side effects include nausea, diarrhoea, constipation, and stomach pain. These often improve over time. Serious side effects are rare but can include severe stomach pain (pancreatitis) or allergic reactions. Always discuss side effects with your prescriber.
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.