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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Tea Helps With Weight Loss — But What About Prescription Options?
Tea contains compounds like catechins and caffeine that may support metabolism, but evidence suggests the effect is modest. If you're considering weight management in the UK, it's worth knowing that prescription weight loss medication is available for eligible adults alongside lifestyle changes like diet and exercise. This guide explains UK-licensed prescription options and how to find out if you qualify.
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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 Medication
Three prescription weight loss medications are currently licensed in the UK: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All three work as GLP-1 receptor agonists (or in Mounjaro's case, a dual GIP/GLP-1 agonist) — they help regulate appetite and may support feeling fuller after meals.
- Mounjaro: A once-weekly injection with doses from 2.5 mg to 15 mg. Clinical trials showed average weight loss of 15–21% of body weight over 72 weeks alongside reduced-calorie diet and exercise.
- Wegovy: A once-weekly injection with doses from 0.25 mg to 2.4 mg. Average weight loss in clinical trials was approximately 14.9% of body weight.
- Saxenda: A daily injection with doses from 0.6 mg to 3 mg — the longest-established GLP-1 option in the UK.
All are prescription-only medicines requiring clinical assessment. Individual results vary significantly, and these are used alongside lifestyle changes, not instead of them.
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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.
Who Is Eligible and How to Access Prescription Weight Loss
Eligibility for prescription weight loss medication in the UK depends on your BMI and health. You may be eligible if you have 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 sleep apnoea. Use our free BMI calculator above to check your personal BMI instantly.
NHS route: Ask your GP about referral to a specialist weight management service (tier 3). Availability varies by region and waiting times can be lengthy.
Private route: Online consultations with UK-licensed prescribers are available without NHS referral. Our GLP-1 weight loss calculator can help you estimate potential outcomes at different doses and compare prescription options available for your weight management journey.
- 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.
Does tea actually help with weight loss?
Tea contains caffeine and catechins which may modestly boost metabolism and fat oxidation. However, the effect is small — typically equivalent to a few hundred calories over weeks. Tea works best alongside a reduced-calorie diet and exercise, not as a standalone solution. For significant weight loss, prescription medication may be more effective for eligible adults.
What's the difference between Mounjaro and Wegovy for weight loss in the UK?
Both are prescription weight loss injections taken once weekly. Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist with higher average weight loss (15–21%) in trials. Wegovy (semaglutide) is a GLP-1 agonist with approximately 14.9% average weight loss. Both require prescription and clinical assessment. Your prescriber will recommend the most suitable option for you.
How do I know if I'm eligible for weight loss medication on the NHS?
NHS eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions. The first step is speaking with your GP, who can assess you and refer you to a specialist weight management service if appropriate. Waiting lists vary significantly by region, so ask your GP about local availability and timescales.
What's the difference between NHS and private weight loss medication access in the UK?
NHS access is through specialist referral services (waiting times vary widely by region). Private access is available through online consultations with UK-licensed prescribers without NHS referral — faster but requires payment. Both routes require clinical assessment, and both medications are the same prescription-only medicines. Private costs typically range from £120–£320 monthly depending on dose.
Can I use MyWeightCheck tools to track my weight loss on prescription medication?
Yes. Our free progress tracker allows you to log your weight loss journey week by week. Combined with our BMI calculator and weight converter, you can monitor your BMI improvements and see your progress in both metric and imperial measurements — helpful for UK adults tracking results alongside prescription treatment.
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.