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 Programs in the UK: Prescription Options Explained
If you're looking for weight management support in the UK, prescription medication options are now available for eligible adults. The NHS and private providers offer several clinically-proven medications alongside lifestyle changes. This guide explains what's available, how to access these programmes, and whether you might be eligible. Understanding your options is the first step towards finding a weight management approach that works 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 Weight Loss Medications: What You Can Access
Three prescription weight loss medications are currently licensed in the UK for weight management:
- Mounjaro (tirzepatide) — a once-weekly GIP and GLP-1 receptor agonist with average weight loss of 15–21% body weight in clinical trials
- Wegovy (semaglutide) — a once-weekly GLP-1 injection with average weight loss of approximately 15% body weight
- Saxenda (liraglutide) — a daily GLP-1 injection, an older option but still available
Eligibility typically requires a BMI of 30 or above, or BMI of 27–29.9 with weight-related conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may have access at lower BMI thresholds due to higher health risks at these levels. All require a prescription and clinical assessment. Use our free BMI calculator to check your personal BMI, and our GLP-1 weight loss calculator to estimate potential results 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 Weight Loss Programmes: How to Find Support
NHS access requires referral to a specialist tier 3 or tier 4 weight management service through your GP. Availability varies significantly by region and waiting lists can be substantial in many areas — sometimes several months. Your GP can assess whether you're eligible and refer you if appropriate.
Private access is available through registered online clinics without NHS referral. You'll have a consultation with a UK-licensed prescriber who assesses your suitability, then a prescription is dispensed by a GPhC-registered pharmacy. This route is faster but involves costs, typically £129–£320+ per month depending on dose.
Starting a weight loss programme works best alongside a reduced-calorie diet and increased physical activity. Use our progress tracker to monitor your weight management journey alongside medication or lifestyle changes.
- 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 do I know if I'm eligible for prescription weight loss medication in the UK?
You're typically eligible if your BMI is 30 or above, or 27–29 with a weight-related health condition like type 2 diabetes or high blood pressure. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may have lower BMI thresholds. Your GP or a licensed prescriber can assess your individual eligibility following a clinical consultation.
What's the difference between NHS and private weight loss programmes?
NHS programmes are free but require GP referral and specialist assessment, with potentially long waiting lists. Private programmes are faster but involve costs (typically £129–£320+ monthly). Both use the same licensed medications; the difference is access speed and cost. Your GP can advise which route suits you.
How much weight can I expect to lose with prescription weight loss medication?
Clinical trials show average weight loss of 15–21% body weight with Mounjaro and approximately 15% with Wegovy over several months, alongside diet and exercise. Individual results vary significantly — some people lose more, some less. Weight loss depends on medication adherence, diet, activity level, and personal factors. Use our GLP-1 calculator for estimates.
Are prescription weight loss injections safe?
Yes, when prescribed by a qualified healthcare professional following clinical assessment. Like all medications, they can cause side effects — commonly nausea and digestive changes — but these usually improve over time. Serious side effects are rare. Your prescriber will monitor you and discuss any concerns. Always report new symptoms to your doctor.
Can I get weight loss medication on the NHS?
Yes, prescription weight loss medication is available on the NHS through specialist tier 3 weight management services. You'll need referral from your GP and assessment by the specialist team. Availability varies by region and waiting times can be long. Speak to your GP about whether you might be eligible and what waiting times are in your area.
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.