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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Fruit Diet For Weight Loss In 7 Days — What The Evidence Shows
A fruit-only diet for 7 days may produce rapid initial weight loss, but it's unlikely to deliver sustainable results or lasting lifestyle change. The NHS recommends a balanced approach combining dietary adjustments with physical activity. For adults struggling with weight management, prescription options are now available in the UK. This guide explores what evidence says about short-term fruit diets and introduces prescription weight loss medications that GPs can prescribe for eligible adults seeking more effective, evidence-based 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.
Prescription Weight Loss Options Available In The UK
For adults looking to lose weight in the UK, prescription medications offer a more sustainable approach than short-term fruit diets. Three UK-licensed weight loss medications are currently available following a clinical assessment with your GP or a prescriber:
- Mounjaro (tirzepatide) — a once-weekly injection that activates dual GIP and GLP-1 hormone pathways. Clinical trials showed average weight loss of 15–21% body weight when combined with diet and exercise.
- Wegovy (semaglutide) — a once-weekly GLP-1 injection. Evidence from the STEP trials demonstrated approximately 15% average body weight loss.
- Saxenda (liraglutide) — a daily GLP-1 injection option for eligible adults.
All three are prescription-only medicines requiring a clinical assessment. Eligibility typically includes adults with a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Use our BMI calculator above to check your starting point, and our GLP-1 weight loss calculator to explore projected 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 Routes — How To Access Weight Loss Support
In the UK, you can access prescription weight loss medication through two routes. NHS access is via referral to a tier 3 specialist weight management service from your GP — though waiting lists vary significantly by region (ICB). Many areas have lengthy delays. Private access is available through GPhC-registered online pharmacies following an online clinical assessment; costs typically range from £129–£320 per month depending on dose.
Whichever route you choose, weight loss medication works best alongside a reduced-calorie diet and increased physical activity — not instead of them. Your GP can discuss which option suits your circumstances. Track your progress using our free progress tracker to monitor results over time, and use the weight converter to switch between kg, stone, and lbs as you log your measurements.
- 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.
Will a fruit-only diet for 7 days help me lose weight permanently?
A fruit-only diet may produce rapid initial water weight loss, but it's unlikely to create lasting results. You'll typically regain weight once you return to normal eating. The NHS recommends sustainable dietary changes combined with physical activity. For significant, sustained weight loss, prescription medications may be more effective for eligible adults.
Who is eligible for prescription weight loss medication in the UK?
Generally, adults with a BMI of 30 or above, or 27 or above with weight-related conditions (type 2 diabetes, high blood pressure, sleep apnoea, cardiovascular disease) may be eligible. Your GP or a licensed prescriber will assess your individual circumstances. Use our BMI calculator to check your starting point.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are once-weekly injections licensed for weight management in the UK. Mounjaro (tirzepatide) activates dual GIP and GLP-1 pathways, while Wegovy (semaglutide) works on GLP-1 alone. Clinical trial data shows both support meaningful weight loss when combined with diet and exercise; individual results vary.
Can I get weight loss medication through the NHS, or do I have to pay privately?
Both options are available in the UK. NHS access is through tier 3 specialist weight management services (referral from your GP), though waiting lists vary by region. Private access is available online without an NHS referral. Your GP can advise which route suits you best.
How much weight can I expect to lose with prescription weight loss medication?
Clinical trials showed average weight loss of 15–21% body weight (Mounjaro) and approximately 15% (Wegovy) over 12–18 months, alongside a reduced-calorie diet and increased physical activity. Individual results vary significantly. Use our GLP-1 weight loss calculator to estimate potential outcomes based on your starting weight and chosen dose.
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.