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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Weight Loss Diet And Exercise Program In The UK
Losing weight sustainably combines dietary changes, increased physical activity, and—for eligible adults—prescription support. The NHS recommends a balanced approach that includes a reduced-calorie diet and regular exercise, with optional medication support for those who qualify. This guide covers evidence-based diet and exercise strategies, UK-licensed weight loss medications, and how to find out if prescription options are available to you. Use our free BMI calculator to assess your current health status and determine next steps.
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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-Licensed Weight Loss Medications And Eligibility
For adults struggling with diet and exercise alone, prescription weight loss medications are available through the NHS and private providers in the UK. Three main options are licensed for weight management:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 injection, once weekly, showing average weight loss of 15–21% in clinical trials
- Wegovy (semaglutide) — a GLP-1 injection, once weekly, with average weight loss of around 15% in trials
- Saxenda (liraglutide) — a GLP-1 injection, once daily, approved for weight management
These medications are prescribed alongside a reduced-calorie diet and exercise programme. Eligibility typically requires a BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions (high blood pressure, type 2 diabetes, or cardiovascular disease). For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds apply. Try our free 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.
Getting Started: NHS Vs Private Routes
The NHS route involves referral to a tier 3 specialist weight management service through your GP. Availability and waiting times vary significantly by region (Integrated Care Board). Many areas have substantial waiting lists.
The private route offers faster access through GPhC-registered online prescribing services following a clinical assessment. Costs range from approximately £129–£320 per month depending on medication and dose.
Whichever route you choose, prescription weight loss medication works best when combined with sustainable dietary changes and regular physical activity. Your GP can assess your individual eligibility and discuss which approach suits you. Use our weight loss progress tracker to monitor your results over time.
- 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's the best weight loss diet for UK adults?
Evidence supports several approaches: a calorie deficit of around 500 kcal/day (roughly 0.5 kg/week loss), Mediterranean-style eating, or structured programmes like the NHS Weight Loss Plan. The "best" diet is one you can sustain long-term. Your GP or a registered dietitian can provide personalised advice based on your health needs.
How much exercise do I need for sustainable weight loss?
The NHS recommends at least 150 minutes of moderate aerobic activity per week (e.g. brisk walking, cycling) plus strength training twice weekly. Exercise supports weight loss and cardiovascular health. Even modest increases in activity help. Combining exercise with dietary changes produces better results than either alone.
Who qualifies for prescription weight loss medication in the UK?
Adults with a BMI of 30 or above, or BMI 27–29.9 with weight-related conditions (diabetes, high blood pressure, heart disease), may qualify. For some ethnic groups, lower thresholds apply. Your GP or a licensed prescriber can assess individual eligibility following a clinical assessment.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist with average weight loss of 15–21%. Wegovy (semaglutide) is a GLP-1 agonist with average weight loss around 15%. Both are once-weekly injections. Individual results vary. Your prescriber will recommend which suits your health profile. Use our BMI calculator to establish your starting point.
Can I stop taking weight loss medication once I've lost weight?
Weight loss medications are typically long-term treatments. Clinical evidence shows weight often returns if medication is stopped without sustained diet and exercise changes. Your prescriber will discuss the appropriate duration and plan for ongoing weight management with 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.