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
Best Protein Powders for Weight Loss in the UK
Protein powders are a popular supplement for weight loss, but if you're struggling with weight management in the UK, you may be eligible for prescription support. Alongside dietary changes like adding protein to your diet, medications like Mounjaro (tirzepatide) and Wegovy (semaglutide) are now available through the NHS and private prescribing for eligible adults. These GLP-1 weight loss injections work differently from supplements — they help regulate appetite and support sustainable weight management. This guide covers protein supplementation and explains the UK prescription weight loss options you might qualify for with your GP.
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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 Medication Available in the UK
If you're looking to lose weight in the UK, prescription weight loss medication is now available and may be more effective than dietary supplements alone. The main options are:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist that helps regulate appetite. Clinical trials showed an average weight loss of 15–21% of body weight over 72 weeks.
- Wegovy (semaglutide) — a GLP-1 injection that supports feeling fuller for longer. Average weight loss was approximately 15% of body weight in clinical trials.
- Saxenda (liraglutide) — a daily GLP-1 injection option, though less commonly used than the once-weekly alternatives.
You may be eligible if you have a BMI of 30 or above, or BMI of 27–29.9 with a weight-related health condition such as type 2 diabetes, high blood pressure, or sleep apnoea. Use our free BMI calculator above to check your personal BMI instantly and discuss medication eligibility with your GP.
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 to Weight Loss Medication
NHS access: Available through specialist tier 3 weight management services following GP referral. Availability varies by region, and waiting lists can be lengthy. Your GP can refer you if you meet eligibility criteria.
Private access: Available through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber. No NHS referral needed. Try our GLP-1 weight loss calculator to explore potential outcomes at different doses, then speak to a prescriber about suitability for your individual health.
Either route typically includes weight loss support alongside medication — dietary advice, activity changes, and progress tracking are important for best results.
- 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 protein powders as effective as prescription weight loss medication?
Protein supplements can support weight loss when combined with a reduced-calorie diet and exercise, but prescription medications like Mounjaro and Wegovy have more robust clinical evidence. Clinical trials showed these medications helped participants lose 15–21% of body weight. Protein is still valuable for preserving muscle mass during weight loss — using both approaches together is often most effective.
How do I know if I'm eligible for prescription 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 like diabetes or high blood pressure. Check your BMI using our free BMI calculator on this page, then discuss medication options with your GP. They can assess your individual circumstances and refer you to specialist services if appropriate.
Can I get weight loss medication through the NHS?
Yes. Prescription weight loss medication is available through NHS specialist tier 3 weight management services. You'll need a GP referral. Availability and waiting times vary significantly by region (ICB). Ask your GP about local services — they can check current referral pathways in your area.
What's the difference between Mounjaro and Wegovy?
Both are once-weekly injections for weight management. Mounjaro is a dual GIP+GLP-1 agonist; Wegovy is a GLP-1 agonist only. Clinical trial data shows both support significant weight loss — around 15–21% and 15% respectively. Individual results vary. Your prescriber will assess which is most suitable for your health profile.
Should I use protein powder alongside prescription weight loss medication?
Yes, protein is valuable when taking weight loss medication. These medications reduce appetite, which can lead to lower overall food intake — including protein. Adequate protein intake helps preserve muscle mass during weight loss. Aim for 1.2–1.6g per kg of body weight daily, using food first, then supplements if needed.
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.