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 Medication Chart — UK Prescription Options
If you're looking for a weight loss chart or guide to prescription medication options available in the UK, this page covers the three main licensed medications, who may be eligible, and how to access them. The NHS supports weight management through specialist services, and prescription treatments like Mounjaro and Wegovy are available for eligible adults. Use our free BMI calculator above to check where you stand, and read on to understand your options for prescription 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 Weight Loss Medications — What's Available
Three prescription medications are licensed in the UK specifically for weight management. Mounjaro (tirzepatide) is a once-weekly injection that activates both GIP and GLP-1 hormone pathways; clinical trials showed average weight loss of around 15–21% of body weight over 72 weeks. Wegovy (semaglutide) is also a once-weekly injection targeting the GLP-1 pathway, with trials demonstrating approximately 15% average weight loss. Saxenda (liraglutide) is a daily injection with similar effects.
All three require a prescription following a clinical assessment. 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. Results vary between individuals, and medication is most effective when combined with dietary changes and increased physical activity.
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.
NHS vs Private Access — How to Get Started
NHS access: Referral to a specialist tier 3 weight management service through your GP is the standard route. However, availability varies significantly across regions, and waiting lists can be lengthy in many areas. Your GP can discuss whether specialist referral is appropriate for you and explain local access pathways.
Private access: GPhC-registered online prescribing services offer faster access following an online clinical assessment with a UK-licensed prescriber. If you're eligible, treatment can begin within days rather than months. Either route requires an honest discussion with a healthcare professional about your health, medications, and weight loss goals. Use the GLP-1 weight loss calculator on this page to estimate potential outcomes at different doses.
- 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 BMI do I need to be eligible for weight loss medication in the UK?
Generally, you may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may qualify at slightly lower thresholds (BMI 27.5 and above) due to higher health risks at lower BMI levels.
How much weight can I expect to lose with Mounjaro or Wegovy?
Clinical trials showed average weight loss of 15–21% of body weight with Mounjaro and around 15% with Wegovy, achieved over several months alongside lifestyle changes. However, individual results vary considerably. Some people lose more, others less. Use our weight loss calculator to see projected ranges based on current weight and medication dose.
Are these weight loss medications available on the NHS?
Yes, NICE has approved tirzepatide (Mounjaro) and semaglutide (Wegovy) for use within NHS specialist weight management services. However, access through the NHS involves referral to a tier 3 specialist service and availability varies by region. Private online prescribing is often faster but involves a cost.
What's the difference between Mounjaro and Wegovy?
Mounjaro uses dual GIP and GLP-1 action, while Wegovy uses GLP-1 alone. Clinical evidence suggests Mounjaro may produce slightly greater average weight loss, but individual response varies. Both are once-weekly injections, and your prescriber will help determine which suits your circumstances.
Can I get a prescription for these medications from my GP directly?
In most cases, weight loss medication prescriptions come through NHS specialist tier 3 services or private prescribers, not routine GP prescriptions. However, your GP is the first point of contact — they can discuss whether you're eligible, refer you to specialist services if appropriate, and advise on local NHS pathways for weight management uk options.
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.