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
High Protein Weight Loss and Prescription Medication in the UK
High protein weight loss is an effective dietary approach that's often combined with prescription weight management medication in the UK. For eligible adults, combining a high protein diet with medicines like Mounjaro or Wegovy may support better weight loss outcomes. This guide explains UK-licensed prescription options, eligibility criteria, and how to access treatment through the NHS or private services. Use our free BMI calculator to check if you might be eligible for prescription support.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Loss Options and Eligibility
Three prescription medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These GLP-1 and GIP/GLP-1 receptor agonist medicines work by reducing appetite and helping you feel fuller, which complements a high protein weight loss diet. Clinical trials showed average weight loss of 15–21% body weight with Mounjaro and approximately 15% with Wegovy when combined with lifestyle changes.
You may be eligible if you have a BMI of 30 kg/m² or above, or BMI 27–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or heart disease. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may qualify at lower BMI thresholds. All three medications are prescription-only and require a clinical assessment before being prescribed.
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
NHS route: Ask your GP for a referral to your local tier 3 specialist weight management service. NHS access is free but availability varies significantly by region, and waiting lists can be several months in many areas. Your GP can discuss whether you're eligible and arrange an assessment.
Private route: GPhC-registered online pharmacies offer prescription weight management following an online clinical assessment with a UK-licensed prescriber. This is available without NHS referral but involves a cost, typically ranging from £129–£320 per month depending on dose and provider. Both routes require a medical assessment to confirm the medication is suitable for you. Our free GLP-1 weight loss calculator can help you explore potential outcomes at different doses.
- 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.
Does high protein diet alone work better than medication?
High protein diets alone can support weight loss through increased satiety and muscle preservation. However, for eligible adults, combining high protein nutrition with prescription medication like Mounjaro or Wegovy may produce better results. Evidence suggests that lifestyle changes and medication together are more effective than either approach alone.
Can I get Mounjaro or Wegovy on the NHS?
Yes, but access is through specialist tier 3 weight management services, not routine GP prescription. You need a GP referral and clinical assessment. NHS access is free but waiting times and availability vary significantly by ICB region. Private access is available faster through online prescribers but involves a cost.
How much weight will I lose on prescription medication?
Individual results vary significantly based on dose, diet, exercise, and personal metabolism. Clinical trials showed average loss of 15–21% body weight with Mounjaro and around 15% with Wegovy over 68–72 weeks, alongside a reduced-calorie diet and increased activity. Your actual results may differ.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist with higher average weight loss (15–21%). Wegovy (semaglutide) is a GLP-1 only medication with average loss around 15%. Mounjaro requires once-weekly 2.5–15mg doses; Wegovy uses once-weekly 0.25–2.4mg doses. Both are prescription-only and require clinical assessment.
How do I know if I'm eligible for prescription weight loss treatment?
You may be eligible if your BMI is 30 or above, or 27–29.9 with weight-related health conditions (diabetes, high blood pressure, heart disease, sleep apnoea). Lower BMI thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults. Use our free BMI calculator to check your BMI, then discuss eligibility with your GP or a private prescriber.
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.