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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Protein Shake for Weight Loss in the UK
Protein shakes can be a useful part of a weight management plan when combined with other healthy lifestyle changes. However, for many people looking to lose weight in the UK, prescription weight management options like GLP-1 injections (Mounjaro and Wegovy) are also available through NHS and private services. This guide explains both dietary approaches and prescription medication options, so you can understand what might work for your situation and discuss options 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.
UK Weight Management Options: Protein Shakes and Prescription Medication
Protein shakes can help with weight management UK by increasing satiety and preserving muscle during calorie deficit. However, they work best alongside reduced-calorie diet and physical activity — they are not a standalone solution.
For eligible adults, the NHS and private prescribers offer prescription weight loss medication licensed in the UK:
- Mounjaro (tirzepatide) — dual GIP/GLP-1 receptor agonist, once-weekly injection, maximum dose 15 mg. Clinical trials showed average weight loss of approximately 15–21% of body weight alongside diet and exercise.
- Wegovy (semaglutide) — GLP-1 receptor agonist, once-weekly injection, maximum dose 2.4 mg. Average weight loss approximately 15% of body weight in clinical trials.
- Saxenda (liraglutide) — GLP-1 receptor agonist, daily injection, maximum dose 3 mg.
All three are prescription-only medicines requiring clinical assessment. They work by helping regulate appetite and are used alongside diet and exercise, not instead of them. Try our free GLP-1 weight loss calculator above to estimate potential results at different doses.
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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 Weight Loss Support in the UK
NHS access: Referral to a tier 3 specialist weight management service from your GP. NICE has approved tirzepatide and semaglutide for eligible adults. Availability varies by region, and waiting times can be significant in many areas.
Private access: Online consultation with a UK-licensed prescriber, prescription issued if clinically appropriate, dispensed by a GPhC-registered pharmacy. No NHS referral needed. Available without waiting lists.
Eligibility: Adults with BMI 30+ or BMI 27+ with weight-related health conditions (type 2 diabetes, prediabetes, high blood pressure, sleep apnoea, cardiovascular disease). Lower thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults. Calculate your BMI using our free tool above and discuss options with your GP — they can advise whether prescription medication is suitable for you and your weight loss medication NHS or private options.
- 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.
Do protein shakes alone help you lose weight?
Protein shakes can support weight loss as part of a calorie deficit, as they increase satiety and help preserve muscle. However, they work best combined with reduced-calorie diet, physical activity, and sustainable lifestyle changes. They are not a substitute for a healthy diet. For significant weight loss, many people benefit from additional support such as prescription medication if eligible.
What is the difference between GLP-1 weight loss injections and protein shakes?
Protein shakes are food supplements that add protein and calories to your diet. GLP-1 injections (like Wegovy and Mounjaro) are prescription medications that regulate appetite hormones and help you feel fuller with smaller portions. They work through a different biological mechanism and are used alongside diet and exercise, not instead of protein or whole foods.
Can I get weight loss injections through the NHS in the UK?
Yes. NICE has approved Mounjaro (tirzepatide) and Wegovy (semaglutide) for NHS use. You need to be referred to a tier 3 specialist weight management service by your GP. Eligibility requires BMI 30+ or BMI 27+ with weight-related health conditions. Availability varies by region, and waiting times can be several months. Ask your GP about your local service.
What is a realistic amount of weight to lose with prescription medication?
Clinical trials show average weight loss of approximately 15–21% of body weight with Mounjaro and 15% with Wegovy, achieved over several months alongside reduced-calorie diet and increased physical activity. Individual results vary significantly. Use our free weight loss calculator to estimate potential outcomes, and discuss realistic expectations with your prescriber.
How do I know if I'm eligible for prescription weight loss medication in the UK?
General eligibility criteria: BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, sleep apnoea, or cardiovascular disease. Lower BMI thresholds apply if you are of South Asian, Chinese, Black African, or Black Caribbean heritage. Calculate your BMI using our free tool and book an appointment with your GP to discuss whether prescription weight management is appropriate for you.
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.