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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Can HRT help with weight loss in the UK?
Hormone replacement therapy (HRT) doesn't directly cause weight loss, but managing menopausal symptoms through HRT may support weight management efforts. If you're struggling with weight and looking for additional help in the UK, prescription weight loss medications like Mounjaro and Wegovy are now available for eligible adults. These GLP-1 and GIP/GLP-1 medications work alongside lifestyle changes to support weight management. Your GP can assess whether you're eligible and discuss the best approach for your individual circumstances.
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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 options
If you're seeking weight management in the UK beyond HRT adjustments, several prescription medications are now available through NHS specialist services or private prescribing:
- Mounjaro (tirzepatide) — a dual GIP/GLP-1 receptor agonist. Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks, alongside a reduced-calorie diet and increased physical activity. Doses range from 2.5 mg to 15 mg once weekly.
- Wegovy (semaglutide) — a GLP-1 receptor agonist with an average weight loss of around 15% at the maximum 2.4 mg dose in clinical trials. Also a once-weekly injection.
- Saxenda (liraglutide) — a once-daily GLP-1 injection, though less commonly prescribed than the weekly options.
All are prescription-only and require clinical assessment to confirm eligibility. Individual results vary significantly, and these medications work best alongside dietary changes and physical activity.
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 and next steps
In the UK, you can access weight loss medication through two routes. NHS access is through specialist tier 3/4 weight management services — your GP can refer you, though waiting times vary significantly by region (ICB). Private access is available through UK-licensed online prescribers following a clinical consultation, with no NHS referral needed.
To find out if you're eligible, book an appointment with your GP to discuss your weight loss journey and overall health. They'll assess your BMI, any weight-related health conditions (such as high blood pressure or type 2 diabetes), and whether prescription medication is appropriate. Use our free BMI calculator to check your current BMI before your appointment — this helps you have a focused conversation with your GP.
- 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 HRT cause weight gain or weight loss?
HRT itself doesn't directly cause weight loss. However, by managing menopausal symptoms like hot flushes and sleep disruption, HRT may indirectly support weight management efforts by improving energy and sleep quality. Weight changes during menopause are complex and influenced by hormones, metabolism, age, and lifestyle. Your GP can discuss HRT's role in your overall health.
What prescription weight loss medications are available on the NHS in the UK?
Mounjaro (tirzepatide) and Wegovy (semaglutide) are the main NHS-available options through specialist weight management services. NICE has approved both for use in tier 3/4 services. Eligibility requires a BMI of 30 or above, or 27 or above with weight-related health conditions. Access varies by region — ask your GP about referral.
How much weight can I expect to lose with Mounjaro or Wegovy?
Clinical trials showed average weight loss of 15–21% with Mounjaro and around 15% with Wegovy at maximum dose over 68–72 weeks. However, individual results vary significantly — some people lose more, some less. These medications work alongside reduced-calorie diet and physical activity, not instead of them.
Can I get prescription weight loss medication privately in the UK?
Yes. Private GPhC-registered online prescribers can assess you and issue a prescription if appropriate, without NHS referral. Costs typically range from £129–£320 per month depending on dose and provider. You still need a valid prescription from a UK-licensed prescriber — these are not over-the-counter medications.
What should I discuss with my GP about weight management?
Bring your BMI (use our free BMI calculator), any weight-related health conditions, and your weight loss goals. Ask about HRT adjustments, referral to NHS specialist services, or whether private prescription medication might be suitable. Your GP can discuss the evidence, side effects, and whether medication fits your individual circumstances.
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.