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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MHRA Weight Loss Medication in the UK
The MHRA (Medicines and Healthcare products Regulatory Agency) has approved several prescription weight management medications for UK adults. These MHRA-approved medications are now available through both NHS specialist services and private prescribing. If you're considering weight management in the UK, understanding your prescription options and eligibility criteria is essential. This guide covers the medications available, who can access them, and how to start a conversation with your GP about weight loss medication suitable for your health needs.
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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.
UK-Licensed Weight Loss Medications
Three MHRA-approved weight management medications are currently available for prescription in the UK. These are prescription-only medicines requiring clinical assessment before being prescribed.
- Mounjaro (tirzepatide) — A dual GIP and GLP-1 receptor agonist, injected once weekly. Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks, alongside a reduced-calorie diet and physical activity.
- Wegovy (semaglutide 2.4 mg) — A GLP-1 receptor agonist, injected once weekly. Trial evidence demonstrated average weight loss of around 15% body weight over 68 weeks in participants following the same lifestyle approach.
- Saxenda (liraglutide 3 mg) — A GLP-1 receptor agonist, injected daily. This was the first GLP-1 medication licensed for weight management in the UK.
All three medications work by affecting appetite regulation and fullness signals, supporting healthier eating patterns. Individual results vary significantly based on personal circumstances, adherence, and lifestyle factors. 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.
Eligibility and Access Routes in the UK
To access MHRA-approved weight loss medication in the UK, you must meet specific eligibility criteria assessed by a licensed prescriber. You may be eligible if you have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 kg/m² with a weight-related health condition such as type 2 diabetes, high blood pressure, or cardiovascular disease. South Asian, Chinese, Black African, and Black Caribbean adults may qualify at lower BMI thresholds due to higher health risks at those levels.
Access routes: Through the NHS via specialist tier 3 weight management services (referral from your GP required, though availability and waiting times vary by region), or through private prescribing services following an online clinical assessment with a UK-licensed prescriber. Your GP can discuss which route is appropriate for your circumstances and help determine if prescription weight loss medication is suitable 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.
What does MHRA approval mean for weight loss medications?
MHRA approval means the medication has been rigorously assessed for safety and effectiveness in the UK. It confirms the medicine is licensed for weight management use. However, approval does not assures it will work for everyone — individual results vary, and medications are prescribed only after clinical assessment of your personal health situation.
Can I get MHRA-approved weight loss medication on the NHS?
Yes, MHRA-approved weight loss medications are available through NHS specialist weight management services. Access is typically through a referral from your GP to a tier 3 or tier 4 service. Availability, waiting times, and specific eligibility vary significantly depending on your local ICB (Integrated Care Board). Contact your GP surgery to enquire about local services.
What if I can't access medication through the NHS?
If NHS waiting lists are long or services aren't available in your area, you can access MHRA-approved weight loss medications through private prescribing. A UK-licensed prescriber conducts an online clinical assessment to determine suitability. Private costs vary by medication and dose, typically ranging from £129–£320 per month depending on the medication chosen.
How do I know if I'm eligible for prescription weight loss medication?
Eligibility is determined by your BMI, health conditions, and medical history. Use our free BMI calculator to check your current BMI category. A GP or licensed prescriber will assess your full health picture and discuss whether medication is appropriate. Book an appointment with your GP to discuss weight management options available to you.
Are these medications assured to help me lose weight?
No medication assures weight loss. MHRA-approved weight loss medications may help support weight loss, but results depend on many factors including adherence to the medication schedule, dietary changes, physical activity, and individual metabolism. Clinical trials showed average weight loss percentages, but individual results vary. Use our progress tracker to monitor your own results over time.
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.