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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Belly Weight Loss Exercise & Medication in the UK
Losing belly fat through exercise is valuable, but exercise alone doesn't always deliver the results you want. In the UK, prescription weight loss medications like Mounjaro and Wegovy are now available for eligible adults, offering a medically-supported approach to weight management. These prescription options work best when combined with exercise and dietary changes. If you're struggling with belly fat and excess weight, understanding what's available through the NHS or private prescribing can help you make an informed decision about the right approach for your situation.
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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 Prescription Weight Loss Options
Three prescription-only weight loss medications are licensed in the UK for adults with excess weight: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). Mounjaro is a dual GIP and GLP-1 receptor agonist, meaning it works on two natural hormone pathways to help reduce appetite and support fullness. Wegovy is a GLP-1 receptor agonist, activating a single hormone pathway. Both are once-weekly injections. Clinical trials showed that on average, patients lost approximately 15–21% of body weight with Mounjaro and around 15% with Wegovy, though individual results vary significantly. These medications are most effective when combined with a reduced-calorie diet and increased physical activity—they support weight management, but don't replace healthy lifestyle changes. Eligibility requires 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.
Clinically BackedWeight Loss
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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.
Accessing Weight Loss Medication in the UK
NHS access is through specialist tier 3 weight management services—your GP can refer you, though waiting lists vary significantly by region. Private access is available through online prescribing services following a clinical assessment; this is faster but comes at a cost. Check your BMI using our free BMI calculator to see if you may be eligible. Before starting any prescription weight loss medication, a licensed prescriber will assess your health, current medications, and suitability. Weight loss medication works best as part of a broader strategy that includes regular exercise, balanced nutrition, and behaviour change—medication removes barriers to these efforts, but doesn't replace them. If you're considering prescription options for belly fat and weight management, speak with your GP or a licensed prescriber to discuss which approach 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.
Can exercise alone shift belly fat without medication?
Yes, regular exercise combined with a calorie deficit can reduce belly fat. However, some people find their progress stalls despite consistent effort. Prescription weight loss medication may help if exercise and diet changes haven't delivered the results you want, especially for stubborn abdominal fat.
How does Mounjaro help with weight loss compared to exercise?
Mounjaro works by reducing appetite and helping you feel fuller after smaller meals. It doesn't replace exercise—rather, it makes it easier to stick to dietary changes and calorie deficit. Combined with regular physical activity, medication can accelerate weight loss that exercise alone may not achieve.
Am I eligible for prescription weight loss medication on the NHS?
You may be eligible if you have a BMI of 30 or above, or 27 or above with a weight-related health condition like diabetes or high blood pressure. Eligibility varies by region, and you'll need a referral to your local NHS specialist weight management service. Your GP can advise on local options.
What's the difference between private and NHS weight loss medication?
NHS access is free but involves referral to specialist services with potential waiting lists. Private prescribing is faster but costs between £129–£320+ per month depending on dose and provider. Both require a prescription from a licensed prescriber and clinical assessment.
Will I need to keep exercising if I take weight loss medication?
Yes. Prescription weight loss medications are most effective alongside regular exercise and a balanced diet. Medication supports these efforts by reducing hunger and cravings, making it easier to maintain the lifestyle changes needed for sustainable weight loss.
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.