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
Free tracker included with every download this week
What Is Zepbound?
Zepbound is a weight management injection approved in the United States, but it is not currently licensed for use in the UK. It contains tirzepatide, the same active ingredient as Mounjaro, which is available to UK adults through the NHS and private prescribing. If you're exploring weight management options in the UK, understanding what Zepbound is and how it relates to treatments you can actually access will help you make informed decisions about your health.
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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.
Zepbound vs UK-Licensed Weight Management Options
Zepbound (tirzepatide) is a prescription-only weight management injection licensed by the US MHRA (Food and Drug Administration) in 2023. It works as a dual GIP and GLP-1 receptor agonist—meaning it activates two natural hormone pathways to help regulate appetite and support feeling fuller after meals. Zepbound is not available in the UK through any route, including the NHS or private prescribing services.
However, the UK has Mounjaro, which contains the identical active ingredient (tirzepatide) at the same doses. Mounjaro is licensed in the UK and available through NHS specialist weight management services and private online prescribing. In clinical trials (SURMOUNT-1), tirzepatide helped participants lose an average of 15–21% of body weight—though individual results vary significantly and depend on dose, lifestyle changes, and personal factors.
For comparison, the UK also offers Wegovy (semaglutide), a GLP-1 agonist (single mechanism rather than dual) licensed for weight management. Use our free GLP-1 weight loss calculator to compare projected weight loss outcomes 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.
How to Access Weight Management Support in the UK
If you're interested in prescription weight management treatment in the UK, your options are clear: Mounjaro is the UK equivalent to Zepbound. Access is available through the NHS via specialist tier 3/4 weight management services—you'll need a referral from your GP, though waiting times vary significantly by region. Privately, you can access Mounjaro through a UK-licensed prescriber following an online clinical assessment.
Before considering any medication, check your BMI using our free BMI calculator to understand your starting point. Adults with a BMI of 30 or above (or 27–29.9 with weight-related health conditions) may be eligible. Your GP can provide personalised NHS guidance, while a private prescriber can assess you for private access. Weight management works best alongside a reduced-calorie diet and increased physical activity.
- 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?
No, Zepbound is not licensed or available in the UK. It is a US MHRA-approved medication only. However, Mounjaro—which contains the identical active ingredient, tirzepatide—is available in the UK through NHS specialist weight management services and private prescribing. If you're in the UK and interested in tirzepatide, Mounjaro is your option.
What is the difference between Zepbound and Mounjaro?
Zepbound and Mounjaro contain exactly the same active ingredient: tirzepatide. The difference is regulatory and geographic. Zepbound is licensed in the USA, while Mounjaro is licensed in the UK, EU, and other markets. They work identically. If you're in the UK, you would access tirzepatide through Mounjaro, not Zepbound.
How does tirzepatide (Zepbound/Mounjaro) work?
Tirzepatide is a dual GIP and GLP-1 receptor agonist. It activates two natural hormone pathways that help regulate appetite, increase feelings of fullness, and support blood sugar control. This dual mechanism may be more effective than single-mechanism injections, though individual results vary based on dose, lifestyle, and personal factors.
Can I import Zepbound from the USA to use in the UK?
Importing prescription medications from abroad for personal use in the UK is not recommended and may be illegal. Additionally, any medication you obtain would not have NHS clinical support. Instead, speak to your GP about accessing Mounjaro through the NHS, or contact a UK-licensed private prescriber for private access to the same active ingredient.
How does Mounjaro compare to Wegovy for weight loss?
Both are prescription-only and licensed in the UK. Mounjaro (tirzepatide, dual mechanism) showed average weight loss of 15–21% in clinical trials. Wegovy (semaglutide, GLP-1 only) showed average weight loss of ~15% in trials. Individual results vary significantly. Use our GLP-1 weight loss calculator to compare projected outcomes, and consult your prescriber about which is appropriate for you.
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.