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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Weight Loss on the NHS — Your Complete Guide to UK Options
The NHS offers several approaches to weight management, from lifestyle support through to prescription medication for eligible adults. If you're overweight or living with obesity, you may qualify for support including specialist services, structured programmes, and in some cases, prescription weight loss medications. This guide explains what's available, how the NHS categorises weight management support, and how to find out if you're eligible for treatment on the health service.
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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-only medications are currently licensed in the UK for weight management in adults: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All three are GLP-1 receptor agonists (Mounjaro is a dual GIP/GLP-1 agonist) that work by helping regulate appetite and blood sugar control.
Eligibility typically includes adults with a BMI of 30 or above, or a BMI of 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or heart disease. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds due to higher health risks at lower weights.
Clinical trials have shown these medications may support meaningful weight loss: Mounjaro helped participants lose an average of 15–21% of body weight, while Wegovy supported approximately 14–15% average weight loss. Individual results vary considerably and are most effective alongside a reduced-calorie diet and increased physical activity. 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
Weight loss medication on the NHS is accessed through specialist tier 3 or tier 4 weight management services, typically following a referral from your GP. Availability varies significantly by region (ICB), and waiting lists can be lengthy in many areas—some regions may have waits of several months to over a year.
Many adults now access prescription weight loss treatment privately through GPhC-registered online pharmacies following a clinical assessment, without waiting for NHS referral. To explore your options, speak with your GP about whether you meet eligibility criteria, what's available in your area, and how long you might wait. Your GP can also discuss whether medication is appropriate for your individual health situation. Use our free BMI calculator above to understand your current BMI category and what this means for your health—this information is helpful to share with your GP during your conversation.
- 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 NHS weight management pathway?
The NHS has a four-tier system: tier 1 (self-help and community programmes), tier 2 (primary care interventions), tier 3 (specialist multidisciplinary services where medication may be prescribed), and tier 4 (bariatric surgery). Your GP can refer you to tier 2 or 3 services depending on your needs and local availability.
Am I eligible for prescription weight loss medication on the NHS?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related conditions like type 2 diabetes, high blood pressure, or sleep apnoea. Lower BMI thresholds apply if you're of South Asian, Chinese, Black African, or Black Caribbean descent. Your GP will assess your individual eligibility and overall health.
How long does it take to access NHS weight loss medication?
Waiting times vary by region. Some areas have relatively short waits of a few weeks, while others may have waits of several months or longer. Contact your local NHS weight management service or ask your GP about current waiting times in your area.
What's the difference between NHS and private weight loss medication access?
NHS access is through specialist services (often with waiting lists) but is free. Private access is through online pharmacies and prescribers, available sooner, but at a cost (typically £129–£320+ per month depending on medication and dose). Both require a clinical assessment and prescription from a UK-licensed prescriber.
Can I switch between NHS and private weight loss medication?
Yes, you can move between NHS and private provision if you choose, though prescriber management and continuity of care may differ. If you're on private treatment and wish to switch to NHS, discuss this with your GP; if waiting for NHS and want to start privately, you can do so independently. Always inform all prescribers of other medications you're taking.
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.