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
Vegan Weight Loss — UK Prescription Options
If you follow a vegan diet and are interested in prescription weight management options, you'll be pleased to know that UK-licensed GLP-1 medications are suitable for vegans. This guide covers the prescription weight loss medications available through the NHS and private prescribing in the UK, how to determine if you're eligible, and how to have a conversation with your GP about prescription weight loss support. Plant-based diets can be part of sustainable weight management, and prescription medication may help alongside dietary and lifestyle changes.
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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.
Prescription Weight Loss Medications Available in the UK
Three prescription-only weight management medications are currently licensed in the UK:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist injected once weekly. Clinical trials showed an average weight loss of 15–21% of body weight over 72 weeks when combined with a reduced-calorie diet and increased physical activity.
- Wegovy (semaglutide) — a GLP-1 receptor agonist injected once weekly. STEP trial data demonstrated approximately 15% average body weight loss at the maintenance dose.
- Saxenda (liraglutide) — a GLP-1 receptor agonist administered daily via injection, with similar efficacy to Wegovy.
All three are vegan-friendly and work by helping regulate appetite and food intake. Individual results vary significantly, and these glp-1 weight loss medications are prescribed only after clinical assessment by a qualified healthcare professional. They're typically used alongside dietary changes, not as a standalone treatment.
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 Eligibility
UK adults may access prescription weight loss medication through either NHS specialist weight management services or private prescribing. NHS access requires referral from your GP to a tier 3 or tier 4 specialist service; availability varies by region and waiting lists can be lengthy. Private access involves an online consultation with a UK-licensed prescriber and dispensing by a GPhC-registered pharmacy.
To be eligible for prescription weight loss treatment in the UK, you typically need a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Use our free BMI calculator to check your personal BMI, then discuss your results and weight management options with your GP to explore what's available for you.
- 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.
Are GLP-1 weight loss injections suitable for vegans?
Yes. Mounjaro, Wegovy, and Saxenda are all vegan-friendly — the active ingredients and most excipients are plant-derived or synthetic. However, always confirm with your prescriber or pharmacist if you have specific ethical concerns about any ingredients or manufacturing processes.
How do I find out if I'm eligible for weight loss medication on the NHS?
Start by calculating your BMI using our free BMI calculator on this page. If your BMI is 30 or above, or 27–29.9 with weight-related health conditions, ask your GP about referral to a specialist weight management service. NHS eligibility and availability vary by region, so early conversation with your GP is important.
Can prescription weight loss medication replace a healthy diet and exercise?
No. Weight loss medications work most effectively alongside a reduced-calorie diet and increased physical activity. They help regulate appetite and support feeling fuller, but sustainable weight management requires lifestyle changes. Your prescriber will discuss this during your clinical assessment.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are once-weekly injections licensed for weight management in the UK. Mounjaro is a dual GIP and GLP-1 agonist; Wegovy is a GLP-1-only medication. Clinical trials showed comparable average weight loss (15–21% for Mounjaro, ~15% for Wegovy), though individual results vary. Your prescriber will assess which is appropriate for you.
How much does prescription weight loss medication cost privately in the UK?
Private costs typically range from £129 to £320 per month depending on the medication and dose. NHS treatment is free if you're eligible and referred through your specialist service. Prices vary between providers, so it's worth comparing options once your prescriber has confirmed eligibility.
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.