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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Natural Weight Loss Methods and Prescription Options in the UK
Weight loss in the UK involves both natural lifestyle approaches and, for eligible adults, prescription medications. While diet, exercise, and behaviour change remain the foundation of sustainable weight management, prescription options like Mounjaro and Wegovy are now available through the NHS and private prescribing for those who meet eligibility criteria. This guide covers what natural weight loss methods are, when prescription support may help, and how to find out if you're eligible for medication-based weight management in the UK.
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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 Prescription Weight Loss Options
Three prescription medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These are GLP-1 and GIP/GLP-1 receptor agonist medications that work by reducing appetite and helping you feel fuller after smaller meals. Clinical trials show that alongside reduced-calorie diet and increased physical activity, these medications may help people lose an average of 15–21% of their body weight — though individual results vary significantly.
Eligibility in the UK: You may be eligible for prescription weight loss medication if you have a BMI of 30 or above, or a BMI of 27–29.9 with at least one weight-related health condition such as type 2 diabetes, high blood pressure, or cardiovascular disease. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply. All prescription medications require a clinical assessment before being prescribed.
Try our free GLP-1 weight loss calculator to estimate potential outcomes at different doses, and use our BMI calculator to check your current BMI category.
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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 and Next Steps
In the UK, you can access prescription weight loss medication through two routes. NHS access is through specialist tier 3 weight management services — you'll typically need a GP referral, and availability varies significantly by region. Waiting lists can be several months to over a year in many areas. Private access is through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber — this is quicker but involves out-of-pocket costs.
If you're interested in exploring prescription weight loss options, start by speaking with your GP about your weight management goals and health history. They can assess your eligibility, discuss whether medication is appropriate for you, and advise on available routes — NHS or private. Your GP can also help you explore natural weight loss methods including dietary support, exercise programmes, and behaviour change strategies tailored to your circumstances.
- 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 are the most effective natural weight loss methods?
The most evidence-based approaches include creating a calorie deficit (roughly 500 kcal per day for ~0.5 kg weekly loss), adopting a balanced diet like the Mediterranean approach, increasing physical activity, and addressing behavioural patterns around eating. The NHS recommends combining dietary changes with increased movement for sustainable results. Even a 5–10% reduction in body weight can bring significant health benefits.
How do I know if prescription weight loss medication is right for me?
Speak with your GP, who can assess your BMI, health history, and weight-related conditions. Prescription medications like Mounjaro and Wegovy are designed for adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions. A licensed prescriber will evaluate whether medication is clinically appropriate for you alongside lifestyle changes.
What's the difference between Mounjaro and Wegovy?
Both are prescription-only once-weekly injections for weight management. Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist with a maximum dose of 15 mg and may result in slightly higher average weight loss. Wegovy (semaglutide) is a GLP-1-only agonist with a maximum dose of 2.4 mg. Both require clinical assessment, and individual results vary.
How long does it take to see weight loss results with prescription medication?
Clinical trials typically measure results over 68–72 weeks. Some people notice appetite changes within 2–4 weeks, but significant weight loss usually becomes apparent over several months. Results are achieved alongside a reduced-calorie diet and increased physical activity — medication works best when combined with lifestyle changes.
Can I access weight loss medication through the NHS?
Yes — Mounjaro and Wegovy are available through NHS specialist weight management services (tier 3). Access requires a GP referral and availability varies by region. Many areas have waiting lists of several months or longer. Your GP can tell you about NHS availability in your area and discuss private options if NHS waiting times are lengthy.
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.