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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What Are the Alternatives to Mounjaro on the NHS?
If you're interested in weight loss medication but Mounjaro isn't available to you through the NHS, or you want to understand other prescription options, Wegovy and Saxenda are approved alternatives in the UK. Both are GLP-1 receptor agonists licensed for weight management. Access depends on your eligibility, local NHS tier 3 services, and whether you pursue NHS or private routes. This guide explains how these alternatives compare, how NHS prescribing works, and what to expect from each option in a UK context.
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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.
NHS Weight Loss Medications and Eligibility
The NHS offers prescription weight loss treatments through specialist tier 3 weight management services, not standard GP prescriptions. Wegovy (semaglutide) and Saxenda (liraglutide) are both approved as alternatives to Mounjaro. NICE has approved all three medications for use within NHS specialist services for adults with:
- BMI of 30 kg/m² or above, or
- BMI of 27–29.9 kg/m² with weight-related health conditions (type 2 diabetes, high blood pressure, heart disease, or sleep apnoea)
- Lower thresholds (from BMI 27.5) for South Asian, Chinese, Black African, and Black Caribbean adults
Unlike Mounjaro, which uses a dual GIP and GLP-1 mechanism, Wegovy is a single GLP-1 agonist. Clinical trials (STEP-1) showed Wegovy helped participants lose around 15% of body weight on average over 68 weeks, alongside diet and exercise. Saxenda, also GLP-1-based, is administered daily rather than weekly. NHS access requires a referral from your GP to a tier 3 service, and availability varies significantly by region.
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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.
NHS vs Private Access to Wegovy
NHS route: Referral to specialist weight management services; can involve waiting lists of several months in some areas; free if approved; limited by regional availability and ICB funding decisions.
Private route: Online consultation with a UK-licensed prescriber; prescription issued if clinically appropriate; dispensed by a GPhC-registered pharmacy; costs typically £129–£320 per month depending on dose; faster access without waiting lists. Both routes require a clinical assessment. Use our free GLP-1 weight loss calculator to estimate potential outcomes at different doses, and our BMI calculator to check your eligibility based on current weight and health conditions.
- 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 Wegovy more effective than Mounjaro?
Clinical trial data shows Mounjaro (tirzepatide) resulted in slightly higher average weight loss (~20% body weight) compared to Wegovy (~15%), but individual results vary significantly. The difference relates to Mounjaro's dual GIP and GLP-1 mechanism versus Wegovy's single GLP-1 mechanism. Both are effective; prescriber choice depends on clinical assessment, availability, and individual factors.
Can I get Wegovy on the NHS instead of Mounjaro?
Yes. If your GP has referred you to a tier 3 NHS weight management service, Wegovy is an option alongside Mounjaro and Saxenda. Availability depends on your local NHS integrated care board (ICB) and specialist service. Waiting lists are often long. If NHS access is limited, private prescribing via a licensed online prescriber is an alternative.
What's the difference between Saxenda and Wegovy?
Both are GLP-1 agonists but differ in delivery: Saxenda (liraglutide) requires a daily injection, while Wegovy (semaglutide) is once weekly. Wegovy showed better average weight loss outcomes in trials. Both require a prescription and clinical assessment. Your prescriber will advise which suits you based on your lifestyle and medical history.
How long do I take Wegovy or Saxenda for?
These are typically long-term treatments. If you stop, weight may gradually return. Treatment usually continues as long as it's effective and well-tolerated. Your prescriber reviews progress regularly and adjusts the dose or medication if needed. Lifestyle changes (diet and exercise) remain important throughout.
Are there other weight loss alternatives besides injections?
Yes. Tier 3 NHS services offer multidisciplinary support including dietary advice, exercise programmes, behavioural therapy, and weight loss surgery (bariatric procedures) for severe obesity. Medications are used alongside, not instead of, these approaches. Your GP can discuss all available options for your situation.
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.