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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Zepbound — UK Health Information Guide
Zepbound is the brand name for tirzepatide, a prescription-only weight management injection available in the US and some international markets. In the UK, tirzepatide is available under the brand name Mounjaro. This guide explains what Zepbound is, how it relates to UK weight management options, and where to find NHS guidance about prescription weight loss treatment. Whether you're exploring healthy weight management or seeking information about GLP-1 medications, understanding your options is the first step towards informed health decisions.
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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.
Zepbound and UK Weight Management Options
Zepbound is the American brand name for tirzepatide, manufactured by Eli Lilly. In the United Kingdom, the same medication is licensed and available under the brand name Mounjaro. Both contain identical active ingredient (tirzepatide) and work in the same way as a dual GIP and GLP-1 receptor agonist — helping to regulate appetite and support weight management through natural hormone pathways.
Tirzepatide (Mounjaro in the UK) is a prescription-only medicine approved by the MHRA for weight management in UK adults. It's administered as a once-weekly injection and comes in doses ranging from 2.5 mg to 15 mg. In clinical trials, tirzepatide helped participants achieve an average weight loss of 15–21% of body weight alongside a reduced-calorie diet and increased physical activity — though individual results vary significantly.
- Available through NHS specialist weight management services or private online prescribing
- Requires clinical assessment before prescription
- Not suitable for pregnant women, those under 18, or people with certain medical conditions
- Most common side effects include nausea, diarrhoea, and stomach discomfort
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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.
Finding Weight Management Support in the UK
If you're exploring weight management options in the UK, the NHS pathway begins with your GP. They can assess your health, calculate your BMI using standard UK measurements, and discuss whether specialist referral to a tier 3 weight management service is appropriate. Many regions now offer tirzepatide (Mounjaro) through NHS specialist services, though availability and waiting times vary by area.
Private access to tirzepatide is also available through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber — this route offers faster access without NHS waiting lists. Whatever path you choose, remember that prescription weight loss medications work best alongside lifestyle changes including balanced nutrition and regular physical activity. Use our free BMI calculator above to assess your personal weight category, and our weight converter if you need to switch between kg, stone, and pounds.
- 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.
Is Zepbound available in the UK?
Zepbound is the US brand name for tirzepatide. In the UK, the same medication is available as Mounjaro. Both contain identical tirzepatide but use different brand names by region. Mounjaro is licensed by the MHRA and available through NHS specialist services and private prescribing routes in the United Kingdom.
How does Zepbound (tirzepatide) work?
Zepbound/tirzepatide is a dual GIP and GLP-1 receptor agonist — it activates two natural hormone pathways to help regulate appetite, reduce food cravings, and support feeling fuller after meals. This dual mechanism may be more effective than single-pathway medications like semaglutide (Wegovy), though individual results vary.
What is the NHS guidance on tirzepatide weight management in the UK?
NICE has approved tirzepatide (Mounjaro) for use within NHS specialist weight management services. NHS access is typically through tier 3 services for adults with a BMI of 30 or above, or 27+ with weight-related health conditions. Your GP can refer you to specialist services, though waiting times vary by region.
Can I get Zepbound on the NHS in the UK?
Tirzepatide is available on the NHS through specialist tier 3 weight management services, usually following GP referral. However, availability, waiting times, and specific criteria vary significantly by region and local ICB. Private access through online prescribing is often faster, though costs apply.
What's the difference between Zepbound and Mounjaro?
Zepbound and Mounjaro contain identical tirzepatide but are different brand names for different regions — Zepbound is the US brand, Mounjaro is the UK brand. The medication, dosing, mechanism, and side effects are exactly the same. If you're in the UK, you'll encounter the name Mounjaro.
Ready to take control of your weight loss journey?
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