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 Diet Weight Loss and Prescription Medication in the UK
A vegan diet can support weight management when combined with a calorie deficit and regular physical activity. However, sustainable weight management in the UK also involves understanding all available options. If you're struggling to lose weight through diet and exercise alone, prescription weight loss medication may be available to you. This guide explains UK-licensed weight management options, eligibility criteria, and how to find out whether prescription medication could help alongside dietary changes like veganism.
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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 Medications
Three prescription-only weight loss medications are currently licensed in the UK for eligible adults: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These are GLP-1 receptor agonist medications (or dual GIP/GLP-1 in Mounjaro's case) that work by regulating appetite and supporting feeling fuller after smaller meals. In clinical trials, adults using these medications alongside a reduced-calorie diet and increased physical activity achieved average weight loss of 15–21% of their body weight, though individual results vary significantly.
- Mounjaro: Once-weekly injection, dual GIP and GLP-1 mechanism, doses from 2.5 mg to 15 mg
- Wegovy: Once-weekly injection, GLP-1 only, doses up to 2.4 mg
- Saxenda: Daily injection, GLP-1 only, doses up to 3 mg
You may be eligible if you have a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. Our free GLP-1 weight loss calculator can help you explore potential 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.
NHS vs Private Access and Next Steps
In the UK, prescription weight loss medication is available through two routes: NHS specialist tier 3 weight management services or private online prescribing. NHS access requires a referral from your GP, though availability and waiting times vary significantly by region. Private access is available through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber, usually without a GP referral.
The first step is to discuss weight management options with your GP, who can assess your individual health profile, BMI, and any weight-related conditions. Your GP can either refer you to your local NHS weight management service or advise you about private options. Use our free BMI calculator to check your current BMI before your appointment — this information will help inform the conversation.
In the UK, prescription weight loss medication is available through two routes: NHS specialist tier 3 weight management services or private online prescribing. NHS access requires a referral from your GP, though availability and waiting times vary significantly by region. Private access is available through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber, usually without a GP referral.
The first step is to discuss weight management options with your GP, who can assess your individual health profile, BMI, and any weight-related conditions. Your GP can either refer you to your local NHS weight management service or advise you about private options. Use our free BMI calculator to check your current BMI before your appointment — this information will help inform the conversation.
- 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.
Can I use prescription weight loss medication while following a vegan diet?
Yes. Prescription weight loss medications like Mounjaro and Wegovy work alongside any dietary approach, including veganism. They support appetite regulation and fullness, which can make it easier to maintain a vegan calorie deficit. Always discuss your dietary preferences with your prescriber during your clinical assessment, as they may have guidance specific to your situation.
Who is eligible for weight loss medication in the UK?
Adults with a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with weight-related health conditions (type 2 diabetes, high blood pressure, cardiovascular disease, sleep apnoea) may be eligible. Eligibility is assessed individually by a prescriber following a clinical consultation. Your GP can discuss whether you meet the criteria.
How long do I need to take weight loss medication?
Duration varies. Some people lose weight and then stop, while others continue long-term to maintain weight loss. This is a decision made between you and your prescriber based on your response to treatment and health goals. Weight loss medication is not a permanent solution alone — ongoing lifestyle changes support sustained results.
What's the difference between NHS and private weight loss medication access in the UK?
NHS access requires a GP referral to a specialist tier 3 weight management service; availability and waiting times vary by region. Private access is through online prescribing services following a clinical assessment, usually without a GP referral, but costs apply. Both routes use the same licensed medications and require prescription-only assessment.
Will weight loss medication work without diet and exercise changes?
No. Weight loss medications work best alongside a reduced-calorie diet and increased physical activity. They support appetite control and fullness, making it easier to sustain dietary changes like a vegan diet, but they are not effective alone. Lifestyle change is essential for both weight loss and long-term health benefit.
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.