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
How Can I Get Weight Loss Injections in the UK?
Weight loss injections are prescription-only medicines available in the UK for eligible adults. Three main options are licensed for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). You can access these either through the NHS or privately. Your eligibility depends on your BMI, health conditions, and individual circumstances. This guide explains the UK pathways, what you need to know, and how to start.
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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 Injections and Eligibility
Three prescription-only weight management injections are licensed in the UK:
- Mounjaro (tirzepatide) — once-weekly dual GIP/GLP-1 agonist injection. Doses range from 2.5 mg to 15 mg weekly. Clinical trials showed average weight loss of 15–21% of body weight alongside diet and exercise.
- Wegovy (semaglutide) — once-weekly GLP-1 agonist injection. Maximum dose 2.4 mg weekly. STEP trials reported approximately 15% average weight loss with lifestyle changes.
- Saxenda (liraglutide) — daily GLP-1 injection. Maximum dose 3 mg daily. Requires daily dosing rather than once-weekly.
Eligibility criteria: You may be eligible if you have a BMI of 30 or above, or 27–29.9 with a weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, or sleep apnoea. Lower BMI thresholds (27.5+) apply for South Asian, Chinese, Black African, and Black Caribbean adults. Use our free BMI calculator above to check your BMI instantly.
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: Speak to your GP about weight management support. If eligible, you may be referred to a specialist tier 3 or tier 4 weight management service. NHS access to these injections is through these specialist services, not routine GP prescription. Availability varies significantly by region and waiting lists can be lengthy. Ask your GP about local services and what the current waiting time is.
Private route: You can obtain a prescription privately through online consultations with UK-licensed prescribers. After a clinical assessment, if approved, a prescription is dispensed by a GPhC-registered pharmacy. This route typically does not require NHS referral and is usually faster, though you pay the full cost. Both routes require a thorough health assessment before prescription.
- 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.
Do I need to see my GP to get weight loss injections?
Yes. Whether accessing through NHS or private prescription, you need a clinical assessment from a UK-licensed healthcare professional or prescriber. Your GP is the best starting point for NHS access. For private access, you'll be assessed through an online consultation. Your medical history, current medications, and health conditions must be reviewed before any prescription can be issued.
What is the difference between Mounjaro and Wegovy?
Both are once-weekly injections, but they work slightly differently. Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Mounjaro clinical trials showed slightly higher average weight loss (15–21% vs approximately 15%), but individual results vary considerably. Your prescriber will assess which is more suitable for you based on your health.
How much weight can I expect to lose?
Clinical trials showed average weight loss of 15–21% of body weight with Mounjaro and approximately 15% with Wegovy — but individual results vary significantly. These results were achieved alongside a reduced-calorie diet and increased physical activity. Weight loss is not assured. Use our GLP-1 weight loss calculator to see projected potential outcomes at different doses based on your starting weight.
How long does it take to get weight loss injections through the NHS?
Waiting times vary considerably by region and local availability. Some areas have waiting lists of several months to over a year for specialist weight management services. Contact your local Integrated Care Board (ICB) or ask your GP about current waiting times in your area. Private access is typically faster, usually within 1–2 weeks of online consultation.
What if I don't meet the BMI criteria?
Standard eligibility is BMI 30 or above (or 27–29.9 with health conditions). However, lower thresholds apply for certain ethnic backgrounds. If you don't currently meet criteria, your GP can discuss other weight management options. Lifestyle interventions, structured weight loss programmes, and other approaches may be recommended first. It's always worth having the conversation with your GP about your individual situation. ```
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.