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 Exercises and Prescription Medication in the UK
Regular physical activity is essential for sustainable weight loss, but exercise alone often needs support to achieve meaningful results. In the UK, prescription weight management medications are now available to eligible adults alongside exercise and dietary changes. This guide explores how exercise fits into a comprehensive weight loss approach and what prescription options you may qualify for through the NHS or privately.
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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 receptor agonists that work by reducing appetite, increasing fullness, and supporting better food choices. In clinical trials, Mounjaro helped participants lose an average of 15–21% of body weight, while Wegovy demonstrated approximately 15% average weight loss — though individual results vary significantly.
- Eligibility: Adults with a BMI of 30 or above, or 27 or above with weight-related conditions (type 2 diabetes, high blood pressure, cardiovascular disease) may qualify
- Prescription-only: All three medications require a clinical assessment by a licensed prescriber
- Combined approach: These medicines work best alongside exercise, dietary changes, and behavioural support — not as a replacement for lifestyle changes
- NHS vs private: NHS access is through specialist tier 3 weight management services; private prescribing is available through GPhC-registered online clinics
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
If you want to explore prescription weight loss support, your first step is speaking to your GP. They can assess your weight, BMI, and health conditions to determine if you're eligible and discuss whether you'd benefit from specialist referral or lifestyle support first. The NHS pathway involves referral to a tier 3 weight management service, though waiting times vary significantly by region.
Alternatively, you can seek a private prescription through an online clinic offering weight management consultations. Either way, prescription medication is combined with exercise and diet for best results. Use our free BMI calculator above to check where you fall on the NHS weight categories, and our GLP-1 weight loss calculator to estimate potential outcomes at different doses. Your GP can then discuss which option suits 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.
How much exercise do I need for weight loss alongside medication?
The NHS recommends at least 150 minutes of moderate aerobic activity per week, plus strength training twice weekly. When combined with prescription weight loss medication, exercise enhances cardiovascular health, preserves muscle during weight loss, and improves long-term outcomes. Even modest increases in daily activity support sustainable results.
Can I lose weight without exercise if I take Mounjaro or Wegovy?
Clinical trials show weight loss occurs with medication alone, but combining it with exercise produces better health outcomes. Exercise prevents muscle loss during weight reduction, improves heart health, and supports maintaining weight loss long-term. Medication is most effective as part of a comprehensive approach including diet and activity.
How do I know if I'm eligible for NHS prescription weight loss medication?
You're potentially eligible if your BMI is 30 or above, or 27 or above with weight-related health conditions. Speak to your GP, who can assess your individual circumstances and refer you to a specialist weight management service if appropriate. Use our BMI calculator to check your starting point.
What's the difference between Mounjaro and Wegovy for weight loss?
Mounjaro (tirzepatide) activates two hormone pathways (GIP and GLP-1), while Wegovy (semaglutide) activates GLP-1 only. Mounjaro showed slightly higher average weight loss (20.9% vs 14.9%) in clinical trials, but both require prescription and clinical assessment. Your prescriber will determine which suits you best.
How long does it take to see results with weight loss medication?
Weight loss typically begins within the first 2–4 weeks, with more significant results after 8–12 weeks of consistent use. Results vary between individuals. Medication works best when combined with sustained exercise and healthy eating. Track your progress over months rather than weeks for realistic expectations.
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.