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
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High Protein Weight Loss Diet — UK Guide
A high protein weight loss diet can be an effective approach to sustainable weight loss when combined with a calorie deficit. Protein helps you feel fuller for longer, preserves muscle during weight loss, and has a higher thermic effect than other macronutrients—meaning your body uses more energy to digest it. In the UK, many people combine dietary changes with other evidence-based weight management methods. This guide explains how protein-focused nutrition works and explores prescription medication options available through the NHS and privately for eligible adults seeking additional support.
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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 Loss Options for Weight Management
If you're looking to lose weight in the UK, prescription medications are available for eligible adults alongside dietary approaches like high protein eating. Three main GLP-1 medications are licensed for weight management:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 agonist, once-weekly injection. Clinical trials showed average weight loss of 15–21% of body weight over 72 weeks.
- Wegovy (semaglutide) — a GLP-1 agonist, once-weekly injection. Evidence suggests average weight loss around 15% of body weight.
- Saxenda (liraglutide) — a GLP-1 agonist, once-daily injection. Similar effectiveness to Wegovy with a different injection schedule.
You may be eligible for weight loss injections if you have a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, high blood pressure, or heart disease. These medications work alongside reduced-calorie diets and increased physical activity—they're not replacements for lifestyle change. Our free GLP-1 weight loss calculator can help you estimate potential weight loss 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 — How to Get Started
NHS access: Prescription weight loss medication is available through specialist tier 3 weight management services. Your GP can refer you, though availability varies significantly by region and waiting lists can be lengthy in many areas. NICE has approved tirzepatide (Mounjaro) for use within NHS services for eligible adults.
Private access: Available through UK-licensed prescribers with an online clinical assessment, dispensed by GPhC-registered pharmacies. This route doesn't require NHS referral. To find out if you're eligible for any prescription weight management option, discuss your BMI, health history, and weight loss goals with your GP or a licensed prescriber. Use our free BMI calculator above to check your starting point, and our weight converter if you need to switch between kg, stone, and pounds for your health records.
- 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 cause weight loss?
High protein supports weight loss by increasing satiety and preserving muscle, but weight loss requires a calorie deficit. Protein helps you eat fewer calories naturally, but you still need to consume fewer calories than you burn. Combining high protein intake with consistent physical activity and monitoring progress using tools like our free progress tracker gives best results.
Can I combine a high protein diet with weight loss medication?
Yes. GLP-1 medications like Mounjaro and Wegovy are designed to be used alongside dietary changes and exercise, not instead of them. In clinical trials, participants combined medication with reduced-calorie diets to achieve weight loss. A high protein approach can work well with these medications, as both support fuller feelings and help preserve muscle mass during weight loss.
How much protein do I need on a weight loss diet?
General guidance suggests 1.6–2.2g of protein per kg of body weight daily during weight loss to preserve muscle. For example, if you weigh 80kg, aim for approximately 128–176g of protein daily. Your GP or a dietitian can give personalised protein recommendations based on your health, activity level, and weight loss goals.
What's the difference between NHS and private weight loss medication in the UK?
Both provide the same prescription medications (Mounjaro, Wegovy, Saxenda). NHS access is through specialist services with potential waiting times; private access is faster but involves direct costs. Both require clinical assessment to ensure the medication is appropriate for you. Eligibility criteria are similar.
How quickly will I lose weight on a high protein diet and medication?
The NHS recommends safe weight loss of 0.5–1kg per week. In clinical trials, GLP-1 medication users lost an average of 15–21% of body weight over 72 weeks—but individual results vary significantly. Combining medication with a high protein diet, calorie deficit, and exercise typically produces the best results.
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.