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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Food for Weight Loss — UK Weight Management Options
While choosing the right foods is essential for sustainable weight loss, many UK adults also benefit from prescription weight management options. The NHS and private prescribers now offer licensed medications like Mounjaro and Wegovy alongside dietary changes. This guide covers both nutritional approaches and medication eligibility. If you're struggling with excess weight, a conversation with your GP about all available options—including prescription support—could be the turning point in your weight management journey.
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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.
Prescription Weight Loss Medication Available in the UK
For adults with a BMI of 30 or above (or 27 or above with weight-related health conditions), three prescription-only medications are licensed for weight management in the UK:
- Mounjaro (tirzepatide) — a once-weekly GIP and GLP-1 receptor agonist injection. Clinical trials showed participants lost an average of 15–21% of body weight alongside dietary changes.
- Wegovy (semaglutide) — a once-weekly GLP-1 receptor agonist. Evidence indicates average weight loss of around 15% body weight in clinical trials.
- Saxenda (liraglutide) — a once-daily GLP-1 injection, approved for prescription weight loss in eligible adults.
All three work by helping regulate appetite and supporting feeling fuller after smaller meals. Results vary significantly between individuals. These medications are used alongside a reduced-calorie diet and increased physical activity, not instead of lifestyle changes. Use our free GLP-1 weight loss calculator to explore potential outcomes at different dose levels.
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 — How to Get Started
NHS route: Your GP can refer you to a tier 3 specialist weight management service in your area. Prescription weight loss medication is available through the NHS for eligible adults, though waiting lists vary significantly by region (ICB). Some areas have availability within weeks; others may have longer delays.
Private route: GPhC-registered online prescribers offer consultations without NHS referral. Following a clinical assessment, a prescription is issued if appropriate. Costs typically range from £129–£320 monthly depending on medication and dose.
Regardless of route, a prescriber will assess your individual health, BMI, and weight-related conditions. Check your BMI using our free calculator to understand your eligibility status, and discuss all options with your GP to choose the approach that suits you best.
- 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.
What foods help with weight loss in the UK?
Foods that support weight loss include lean proteins (chicken, fish, eggs), whole grains, plenty of vegetables, legumes, and fruit. Prioritise foods high in fibre and protein as they help you feel fuller for longer. Reduce ultra-processed foods, sugary drinks, and high-calorie snacks. The NHS recommends a balanced, reduced-calorie diet—aim for a deficit of around 500 kcal daily for sustainable loss of approximately 0.5 kg per week.
Is prescription weight loss medication available on the NHS in the UK?
Yes. Mounjaro (tirzepatide) and Wegovy (semaglutide) are both approved for NHS use through specialist tier 3 weight management services. Your GP can refer you if you have a BMI of 30 or above, or 27 or above with weight-related health conditions like type 2 diabetes or high blood pressure. NHS availability varies by region; private options are also available.
How much weight can you lose with prescription medication?
Clinical trials show Mounjaro users lost an average of 15–21% body weight, and Wegovy users around 15%, though individual results vary significantly. Weight loss depends on the specific medication, dose, adherence, and lifestyle changes alongside the injection. Always use conditional language—results are not assured, and your GP or prescriber can discuss realistic expectations based on your personal health.
Can I use food changes and medication together for weight loss?
Absolutely. Prescription weight loss medications are designed to work alongside dietary changes and increased physical activity—not replace them. The best approach combines food choices (whole grains, lean proteins, vegetables), regular movement, and medical support if eligible. This combination gives you the best chance of sustainable weight loss and long-term health improvement.
How do I know if I'm eligible for weight loss medication in the UK?
Calculate your BMI first using our free BMI calculator. Adults with a BMI of 30 or above are generally eligible; those with a BMI of 27–29.9 may be eligible if they have weight-related health conditions (diabetes, high blood pressure, etc.). Your GP or a prescriber will do a full clinical assessment to confirm eligibility and discuss whether medication is right for you.
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.