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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NHS Weight Loss App and Prescription Medication Options in the UK
The NHS offers several weight management approaches, from digital tools to prescription medication. While many people start with the NHS Weight Loss Plan app and lifestyle support, eligible adults with overweight or obesity can access prescription weight loss medication through NHS specialist services. This guide explains your options, eligibility criteria, and how to find out if medication might be right for you.
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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 Prescription Weight Loss Medications
Three prescription medications are currently licensed in the UK for weight management in adults: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These are GLP-1 receptor agonist medications (or dual GIP/GLP-1 in Mounjaro's case) that work by reducing appetite and helping you feel fuller after smaller meals.
- Mounjaro: Once-weekly injection, doses from 2.5 mg to 15 mg. Clinical trials showed average weight loss of 15–21% body weight.
- Wegovy: Once-weekly injection, doses up to 2.4 mg. Clinical evidence suggests approximately 15% average body weight loss.
- Saxenda: Daily injection, maximum dose 3 mg. Effective for weight loss alongside reduced-calorie diet and increased activity.
All three are prescription-only medicines requiring clinical assessment before being prescribed. Try our GLP-1 weight loss calculator to estimate potential outcomes at different doses.
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 and Eligibility
NHS access: Prescription weight loss medication is available through NHS specialist tier 3 weight management services. You'll typically need a GP referral, and availability varies significantly by region. Waiting lists can be lengthy in some areas. Your GP can assess whether referral is appropriate based on your BMI and health conditions.
Eligibility: Generally, adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions (such as type 2 diabetes, hypertension, or sleep apnoea), may be eligible. South Asian, Chinese, Black African, and Black Caribbean adults have lower BMI thresholds. Calculate your BMI using our free BMI calculator to understand where you currently stand.
Private access: Licensed prescribers can issue prescriptions following an online clinical assessment, available without NHS referral. Discuss all options with your GP to find the right path for you.
Weight loss medication works best alongside lifestyle changes: reduced-calorie diet, increased physical activity, and behaviour support. The NHS Weight Loss Plan app provides free digital guidance on nutrition and exercise. Your GP or specialist can discuss whether prescription medication is suitable for your individual circumstances and 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.
What is the difference between the NHS Weight Loss Plan app and prescription weight loss medication?
The NHS Weight Loss Plan app is a free digital tool providing diet and exercise guidance, suitable for anyone wanting to lose weight. Prescription medications like Mounjaro and Wegovy are prescription-only treatments for eligible adults, used alongside lifestyle changes for more intensive weight management support.
How do I know if I'm eligible for prescription weight loss medication on the NHS?
Generally, you may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure. Lower thresholds apply for certain ethnicities. Speak to your GP, who can assess your individual eligibility and refer you to specialist services if appropriate.
How long are NHS waiting lists for weight management medication?
Waiting times vary significantly by region and local NHS services. Some areas have waiting lists of several months to over a year. Ask your GP about typical waiting times in your area, and ask about private options if NHS wait times are a concern.
Can I get weight loss injections like Mounjaro or Wegovy through the NHS?
Yes, Mounjaro and Wegovy are available through NHS specialist weight management services following referral from your GP. However, availability depends on your region. NICE has approved these medications for NHS use, but implementation varies across different NHS regions and trusts.
What should I do first if I'm interested in prescription weight loss help?
Start by speaking to your GP about your weight management goals. They can assess your BMI (calculate it using our free BMI calculator if helpful), discuss your health, and advise whether referral to specialist services or other support is appropriate. Be honest about your weight loss attempts and any health conditions.
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.