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
Vegetarian Diet for Weight Loss in the UK
A vegetarian diet can support weight loss when combined with a calorie deficit and regular physical activity. Plant-based eating offers benefits including higher fibre content, lower saturated fat, and sustained energy levels. However, sustainable weight loss depends on overall calorie balance and lifestyle changes. For adults struggling to lose weight through diet and exercise alone, prescription weight management options are available in the UK. Your GP can discuss whether medication might be suitable alongside dietary 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.
UK Prescription Weight Management Options
If you're working towards weight loss and have a BMI of 30 or above (or 27–29.9 with weight-related health conditions), you may be eligible for prescription weight loss medication in the UK. Three main options are currently licensed:
- Mounjaro (tirzepatide) — a once-weekly dual GIP and GLP-1 injection; clinical trials showed average weight loss of 15–21% of body weight
- Wegovy (semaglutide) — a once-weekly GLP-1 injection; trials demonstrated average weight loss of around 15% of body weight
- Saxenda (liraglutide) — a once-daily GLP-1 injection; supported by long-term safety and efficacy data
All three work best when combined with a reduced-calorie diet and increased physical activity — they are not replacements for lifestyle changes. Individual results vary significantly. Use our free GLP-1 weight loss calculator to explore potential outcomes at different medication doses, and our BMI calculator to check your current eligibility category.
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 — How to Get Started
In the UK, prescription weight loss medication is available through two routes. The NHS route involves referral to a specialist tier 3 or tier 4 weight management service from your GP; however, availability varies significantly by region and waiting lists can be lengthy. The private route involves an online consultation with a UK-licensed prescriber, and medication is dispensed by a registered pharmacy if you're clinically suitable — this avoids NHS waiting times but involves cost.
Start by speaking with your GP about your weight management goals. They can assess your health, calculate your BMI, discuss whether you meet eligibility criteria, and explain both NHS and private options. Your GP can also help rule out underlying conditions and ensure any medication is appropriate alongside your vegetarian diet plan. Track your progress with our free progress tracker as you implement dietary and lifestyle changes.
- 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 a vegetarian diet help me lose weight?
Yes. A well-planned vegetarian diet rich in vegetables, pulses, whole grains, and nuts can support weight loss through higher fibre intake, lower calorie density of plant foods, and reduced saturated fat. Weight loss ultimately depends on maintaining a calorie deficit, so portion control and overall energy balance remain essential. Combining a vegetarian diet with increased physical activity produces the best results.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are once-weekly injections licensed for weight loss in the UK. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist showing average weight loss of 15–21% in trials. Wegovy (semaglutide) is a GLP-1 agonist showing average weight loss of around 15%. Both require prescription and clinical assessment. Your prescriber will recommend the most suitable option based on your individual health profile.
How do I know if I'm eligible for weight loss medication in the UK?
You may be eligible if you have 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. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may have lower eligibility thresholds. Use our BMI calculator to check your category, then discuss eligibility with your GP.
Will prescription weight loss medication work without diet changes?
No. UK-licensed weight loss medications work best alongside a reduced-calorie diet and increased physical activity. They help reduce appetite and support feeling fuller, but they are not replacements for lifestyle changes. Sustainable weight loss requires both medication support (if prescribed) and behaviour change. Your GP or prescriber will discuss realistic expectations during your consultation.
What weight loss can I expect with prescription medication?
Clinical trials show average weight loss of 15–21% of body weight over 68–72 weeks, depending on the medication and dose. However, individual results vary significantly based on your starting weight, adherence, diet, exercise, and metabolism. Our GLP-1 weight loss calculator can help project potential outcomes. Always remember that results are estimates — your actual experience may differ.
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.