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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Decreased Appetite and Weight Loss — Prescription Options in the UK
Decreased appetite can be a powerful tool for weight loss when supported by the right approach. In the UK, several prescription medications are now licensed to help reduce appetite and support sustainable weight management. These medicines work by mimicking natural hormones that signal fullness to the brain. If you're struggling with appetite control and excess weight, understanding your options — both through the NHS and privately — can help you make an informed decision with your GP about what's right for you.
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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-Licensed Weight Management Medications That Reduce Appetite
Three prescription medications are currently licensed in the UK specifically for weight management and appetite control:
- Mounjaro (tirzepatide) — a once-weekly injection that activates dual GIP and GLP-1 hormone pathways. Clinical trials showed participants lost an average of 15–21% of their body weight, with most reporting reduced appetite and earlier feelings of fullness.
- Wegovy (semaglutide) — a once-weekly GLP-1 receptor agonist injection. In clinical trials, participants achieved an average weight loss of around 15% of body weight alongside reduced-calorie diet and increased physical activity.
- Saxenda (liraglutide) — a once-daily GLP-1 injection, offering an alternative for those who prefer daily dosing.
All three are prescription-only medicines and require clinical assessment before being prescribed. Eligibility typically includes adults with a BMI of 30 or above, or BMI of 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Use our free GLP-1 weight loss calculator to explore potential outcomes at different doses.
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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.
How to Access Weight Loss Medication in the UK
NHS route: Your GP can refer you to a specialist tier 3 weight management service, where a multidisciplinary team assesses eligibility and prescribes medication if appropriate. NHS access varies significantly by region and waiting lists can be lengthy in some areas.
Private route: You can access prescription weight loss treatment through a GPhC-registered online pharmacy following an online clinical assessment with a UK-licensed prescriber. This route does not require an NHS referral and is typically faster, though costs apply.
Start by discussing with your GP whether prescription weight loss medication may be suitable for you based on your BMI, health history, and weight loss goals. Calculate your personal BMI using our free BMI calculator above, then bring this information to your appointment. Track your progress alongside any treatment using our free progress tracker.
- 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 does prescription medication reduce appetite?
These medications are GLP-1 receptor agonists (or dual GIP/GLP-1 agonists in the case of Mounjaro). They mimic natural gut hormones that signal fullness to your brain, slow gastric emptying so food leaves your stomach more slowly, and reduce hunger signals. This helps you feel satisfied with smaller portions and experience fewer food cravings throughout the day.
What's the difference between Mounjaro and Wegovy for appetite control?
Mounjaro (tirzepatide) activates two hormone pathways — GIP and GLP-1 — offering potentially stronger appetite suppression. Wegovy (semaglutide) activates GLP-1 only. Clinical trials suggest Mounjaro may produce slightly greater average weight loss, but both effectively reduce appetite. Individual response varies significantly, and your prescriber will recommend the most suitable option based on your health profile.
Am I eligible for prescription appetite-suppressing medication on the NHS?
Generally, yes, if you have a BMI of 30 or above, or BMI of 27–29.9 with a weight-related health condition such as type 2 diabetes, hypertension, or sleep apnoea. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply. Ask your GP about referral to your local specialist weight management service.
How quickly will appetite reduction start after beginning medication?
Most people notice reduced appetite within the first 2–4 weeks of starting treatment. However, this varies between individuals. Your prescriber will start you on a lower dose and gradually increase it every 4 weeks. Side effects like nausea may initially reduce appetite further, but this typically subsides as your body adjusts.
Can I use appetite-suppressing medication without changing my diet and exercise?
These medications work most effectively alongside a reduced-calorie diet and increased physical activity. They are tools to support sustainable weight loss, not replacements for lifestyle changes. Evidence shows the best results occur when medication is combined with behaviour change. Your GP or specialist will discuss this as part of your treatment plan.
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.