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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Best Diets for gradual weight management in the UK
When you're looking for the best diets for gradual weight management in the UK, it's important to know that sustainable results combine dietary changes with professional support. The NHS recommends weight loss of 0.5–1 kg per week as the safest approach, though prescription weight management medication can support faster results for eligible adults. This guide covers evidence-based dietary strategies alongside UK-licensed weight loss medication options you can discuss with your GP, including how to check your eligibility and understand what results to expect.
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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
For adults seeking gradual weight management support, UK-licensed prescription medications are available through NHS specialist services or private prescribing. The most widely discussed options are Mounjaro (tirzepatide) and Wegovy (semaglutide), both once-weekly injectable medications that may help reduce appetite and support weight management uk efforts alongside diet and exercise.
- Mounjaro: Dual GIP/GLP-1 agonist; clinical trials showed average weight loss of 15–21% of body weight over 72 weeks at maximum dose
- Wegovy: GLP-1 agonist only; average weight loss around 15% of body weight in clinical trials
- Saxenda: GLP-1 agonist; daily injection option with average weight loss of 5–10% of body weight
These are prescription-only medicines requiring clinical assessment. Eligibility typically includes adults with a BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions. Our GLP-1 weight loss calculator can help you estimate potential outcomes at different doses, though individual results vary significantly.
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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, prescription weight loss medication can be accessed through two routes. NHS weight loss medication is available through tier 3 specialist weight management services, usually requiring a GP referral; however, waiting lists vary by region and availability can be limited. Private prescribing offers faster access through GPhC-registered online pharmacies following a clinical assessment, typically at costs ranging from £129–£320 per month depending on dose.
Start by discussing your weight loss goals with your GP, who can assess whether you meet eligibility criteria and refer you to specialist services if appropriate. Your GP can also review your medical history to ensure any medication is safe for you. Use our free BMI calculator to understand your current health status, then have a focused conversation with your healthcare provider about which option—NHS or private—suits your circumstances best.
- 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.
What is the fastest safe weight loss diet in the UK?
The NHS recommends losing 0.5–1 kg per week through a calorie deficit of around 500 kcal per day, achieved via diet and exercise. Very gradual weight management (>1.5 kg/week) risks muscle loss and nutritional deficiencies. Prescription medications like Mounjaro or Wegovy can support faster results when combined with lifestyle changes, but should only be used under medical guidance.
Is Mounjaro available on the NHS for gradual weight management?
Mounjaro is available through NHS specialist weight management services for eligible adults (BMI ≥30, or BMI 27–29.9 with health conditions). Access varies by region and typically requires GP referral to tier 3 services. Waiting times can be lengthy. Private prescribing via a licensed UK prescriber offers faster access but involves costs.
How quickly can you lose weight with Wegovy or Mounjaro?
Clinical trials showed average weight loss of 15–21% of body weight over 12–18 months alongside diet and exercise. Individual results vary significantly based on dose, adherence, and lifestyle changes. These medications support weight loss—they do not assures specific outcomes. Your GP can discuss realistic expectations based on your personal health.
What diet works best with GLP-1 weight loss medication?
GLP-1 medications (like Wegovy or Mounjaro) work alongside reduced-calorie, balanced diets. The Mediterranean diet has strong evidence for long-term sustainability. Low-calorie approaches (around 1200 kcal/day) may be suggested by your prescriber. Combine whichever diet you choose with increased physical activity for best results and discuss dietary support options with your GP.
How do I check if I'm eligible for weight loss medication in the UK?
You're typically eligible if you have a BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions (diabetes, high blood pressure, sleep apnoea, etc.). Lower thresholds apply for South Asian, Black African, or Black Caribbean adults. Use our free BMI calculator to check your BMI, then discuss eligibility with your GP or a licensed prescriber.
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.