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 and Decreased Appetite: UK Medication Options
Decreased appetite is a common side effect of prescription weight loss medications available in the UK. If you're experiencing appetite suppression and interested in structured weight management, several GLP-1 and dual-action medications are licensed for UK use. These prescription options work alongside dietary changes and physical activity. This guide explains how these medications work, who is eligible, and how to access them through the NHS or private prescribing. Always discuss any weight management plans with your GP first.
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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 Loss Medications That Reduce Appetite
Three prescription weight loss medications are currently licensed in the UK for adults with excess weight or weight-related health conditions:
- Mounjaro (tirzepatide) — A dual GIP and GLP-1 receptor agonist that may help reduce appetite and support feeling fuller after meals. Typical doses range from 2.5 mg to 15 mg, injected once weekly. Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks, though individual results vary significantly.
- Wegovy (semaglutide) — A GLP-1 receptor agonist available in doses from 0.25 mg to 2.4 mg, also injected once weekly. In clinical trials, participants achieved an average weight loss of approximately 15% of body weight, alongside a reduced-calorie diet and increased physical activity.
- Saxenda (liraglutide) — A daily GLP-1 injection offering a different dosing schedule. All three work on similar appetite-regulation mechanisms but have different dosing protocols and clinical evidence profiles.
These medications may help reduce appetite, but they are prescription-only and require a clinical assessment to determine if they're suitable for your individual health situation. Use our free GLP-1 weight loss calculator above to explore potential weight loss projections 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.
Eligibility and Accessing Weight Loss Medication in the UK
You may be eligible for prescription weight loss medication in the UK if you have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. South Asian, Chinese, Black African, and Black Caribbean adults may qualify at lower BMI thresholds due to higher health risks at those levels.
NHS access: Referral to a tier 3 specialist weight management service through your GP. Waiting times vary significantly by region. Private access: Through a GPhC-registered online pharmacy with a UK-licensed prescriber, available without NHS referral. Check your personal eligibility and BMI using our free BMI calculator on this page, then speak with your GP about your options for weight management support.
- 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.
Will prescription weight loss medication suppress my appetite completely?
No. These medications help reduce appetite and increase feelings of fullness, but they don't eliminate hunger completely. Effects vary between individuals. Some people experience significant appetite reduction while others notice a more modest change. Your prescriber can discuss what to expect based on your health profile.
Can I get weight loss medication on the NHS in the UK?
Yes, through NHS specialist tier 3 weight management services. You'll need a GP referral. However, NHS availability varies by region and waiting lists can be lengthy. Private prescribing is also available through online consultations with UK-licensed prescribers, though this involves costs.
How quickly will I see weight loss results from these medications?
Results typically become noticeable within 4–8 weeks, though individual timelines vary. Clinical trials tracked results over 12–18 months. These medications work best alongside a reduced-calorie diet and increased physical activity. Progress tracking alongside medication is recommended.
Are these weight loss medications safe to use long-term?
These medications have been studied in clinical trials lasting up to 72 weeks. Longer-term safety data continues to be gathered. Side effects often decrease over time as your body adjusts. Your prescriber will monitor your health regularly and discuss whether continued use is appropriate for you.
What happens to appetite when I stop taking weight loss medication?
Appetite typically returns to previous levels within weeks of stopping the medication. Weight regain can occur if lifestyle changes (diet and activity) aren't maintained. This is why these medications are most effective when combined with sustained behaviour change and supported by a healthcare professional.
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.