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
Why Is Protein Good for Weight Loss?
Protein is one of the most important nutrients for weight loss because it helps you feel fuller for longer, maintains muscle mass during weight loss, and requires more energy to digest than other nutrients. In the UK, combining a protein-rich diet with lifestyle changes—and for eligible adults, prescription weight management options—creates the best foundation for sustainable weight loss. Understanding how protein supports your goals can help you make informed decisions about your overall approach to weight management.
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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.
How Protein Supports Weight Loss and UK Medication Options
Protein helps weight loss in several proven ways: It increases satiety, meaning you feel satisfied after eating smaller portions. Your body also burns more calories digesting protein compared to carbohydrates or fat—a process called the thermic effect of food. Protein preserves lean muscle mass during calorie deficits, which is crucial because muscle tissue burns more calories at rest than fat tissue.
For adults in the UK with a BMI of 30 or above (or 27–29.9 with weight-related health conditions), prescription weight management medications are now available alongside dietary changes. Mounjaro (tirzepatide) and Wegovy (semaglutide) are once-weekly injections licensed in the UK that work by reducing appetite and helping you eat less naturally. Clinical trials showed Mounjaro users lost an average of 15–21% of body weight, and Wegovy users approximately 15%, though individual results vary significantly. These medications work best when combined with a protein-rich diet and increased physical activity.
- Protein targets: aim for 1.6–2.2g per kg of body weight daily during weight loss
- Good protein sources: chicken, fish, eggs, Greek yogurt, lentils, beans, tofu
- Prescription options require assessment by a GP or licensed prescriber—eligibility varies
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.
Getting Prescription Weight Management in the UK
If you're interested in prescription weight loss support alongside dietary changes, there are two main routes in the UK. NHS access: Ask your GP for a referral to a specialist tier 3 weight management service. Availability varies significantly by region, and waiting lists can be lengthy. Private access: You can consult a UK-licensed prescriber online for assessment—if eligible, a prescription is dispensed by a regulated pharmacy.
Before starting any weight loss plan, calculate your BMI using our free BMI calculator to understand your baseline. Track your progress throughout your journey using our free progress tracker, which logs weight changes over time. A GP can advise whether prescription medication is appropriate for you based on your health, BMI, and any existing conditions. The combination of adequate protein intake, calorie awareness, and professional support—whether through lifestyle alone or with medication—gives you the best chance of sustainable success.
- 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.
How much protein should I eat daily for weight loss?
A common target is 1.6–2.2g of protein per kilogram of body weight daily. For example, an 80kg adult would aim for 128–176g protein daily. This supports muscle preservation and increases satiety. Your GP or a registered dietitian can personalise recommendations based on your activity level and goals.
Can I lose weight with diet and exercise alone, or do I need medication?
Many people achieve weight loss through diet and exercise alone. However, if you have a BMI of 30 or above (or 27 or above with weight-related health conditions), prescription medications like Mounjaro or Wegovy may be an option to discuss with your GP. Medication works best alongside lifestyle changes, not instead of them.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are once-weekly injections licensed in the UK for weight management. Mounjaro (tirzepatide) is a dual GIP and GLP-1 medication with average weight loss of 15–21% in trials. Wegovy (semaglutide) is a GLP-1 medication with average weight loss around 15%. Both require prescription and clinical assessment. Individual results vary considerably.
How do I find out if I'm eligible for prescription weight loss medication in the UK?
Speak with your GP about your weight and health. You may be eligible if your BMI is 30 or above, or 27–29.9 with weight-related conditions like type 2 diabetes or high blood pressure. Your GP can refer you to NHS specialist services or advise on private options through a licensed prescriber.
Does prescription weight loss medication work without changing diet and exercise?
No. Mounjaro, Wegovy, and other weight loss medications work best alongside a reduced-calorie diet and increased physical activity. These medications help reduce appetite and support feeling fuller, but sustainable weight loss requires lifestyle changes. Clinical trials show results when medication is combined with diet and exercise support.
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.