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 Help — Medication & Support Available in the UK
If you're looking for weight loss help through the NHS, several options are available depending on your BMI and health circumstances. The NHS offers a tiered approach to weight management, including prescription medications for eligible adults. This guide explains what prescription weight loss medication is available in the UK, who qualifies, and how to access NHS support or private treatment options. Understanding your options helps you make informed decisions about weight management alongside lifestyle changes.
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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 medicines are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All three are GLP-1 receptor agonists (or in Mounjaro's case, a dual GIP and GLP-1 agonist) that help reduce appetite and support feeling fuller after meals.
- Mounjaro: Once-weekly injection, doses from 2.5 mg to 15 mg. Clinical trials showed average weight loss of 15–21% body weight at the highest dose.
- Wegovy: Once-weekly injection, doses up to 2.4 mg. Average weight loss around 15% body weight in clinical trials.
- Saxenda: Once-daily injection, doses up to 3 mg. Available longer in the UK, evidence supports sustained weight loss.
All require a prescription and clinical assessment. Individual results vary significantly. Weight loss medications work best alongside a reduced-calorie diet and increased physical activity. Your prescriber will assess which option suits your health profile.
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 How to Access NHS or Private Support
You may be eligible for prescription weight loss medication if you have a BMI of 30 or above, or a BMI of 27–29.9 with at least one weight-related health condition (such as type 2 diabetes, high blood pressure, or sleep apnoea). Check your BMI using our free BMI calculator above.
NHS access: Referral is typically through specialist tier 3 weight management services, accessed via your GP. Availability varies by region and waiting lists can be lengthy.
Private access: Available through GPhC-registered online pharmacies following a clinical assessment. No NHS referral needed, though costs apply.
Either way, start by discussing weight loss options with your GP, who can assess your individual circumstances and guide you toward the most appropriate pathway.
- 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.
How much weight can I expect to lose with NHS weight loss medication?
Clinical trials show average weight loss of 15–21% body weight with Mounjaro and around 15% with Wegovy, achieved alongside diet and exercise. Individual results vary significantly — some people lose more, others less. Your GP can discuss realistic expectations for your situation. Use our GLP-1 weight loss calculator to estimate potential outcomes at different doses.
What's the difference between NHS and private weight loss medication access in the UK?
NHS access is through specialist weight management services (usually tier 3), accessed via GP referral. Private access is available through online clinics without referral. NHS is free but may have waiting lists; private costs £129–£320+ monthly depending on dose. Both require a prescription and clinical assessment.
Am I eligible for NHS weight loss medication if my BMI is 27?
You may be eligible if your BMI is 27–29.9 AND you have a weight-related health condition (diabetes, high blood pressure, sleep apnoea, etc.). If your BMI is below 27, discuss other weight management options with your GP. Use our BMI calculator above to check your current BMI.
How do I ask my GP about weight loss medication?
Book an appointment and explain you're interested in exploring prescription weight loss options. Your GP will assess your BMI, health history, and any weight-related conditions. They can refer you to specialist services, discuss private options, or recommend lifestyle support first. Bringing a list of your current medications and health concerns helps.
Are weight loss injections safe?
Prescription weight loss medications are licensed and have undergone rigorous safety testing. Common side effects include nausea and diarrhoea, which often ease over time. Serious side effects are rare. However, they're not suitable for everyone — pregnant women, those with certain medical conditions, or people taking specific medications may not be eligible. Your prescriber assesses safety individually.
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.