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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Topiramate and Weight Loss Dosage in the UK
Topiramate is an anticonvulsant medication sometimes used off-label for weight management, though it is not licensed for this purpose in the UK. If you're exploring weight management options, it's important to understand what prescription weight loss treatments are actually available through the NHS and private prescribing in the UK, and how they compare. Your GP can advise whether any medication is suitable for your individual health needs. This guide explains the landscape of licensed weight management medication in the UK and how to access support.
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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 Management Medications
Unlike topiramate, several medications are specifically licensed for weight management in the UK and represent safer, evidence-based options:
- Mounjaro (tirzepatide) — a dual GIP/GLP-1 receptor agonist approved for weight management in adults with a BMI of 30 or above, or 27 or above with weight-related health conditions. Clinical trials showed average weight loss of 15–21% body weight.
- Wegovy (semaglutide) — a GLP-1 receptor agonist approved for similar eligibility criteria, with average weight loss of approximately 15% body weight in trials.
- Saxenda (liraglutide) — a daily GLP-1 injection also licensed for weight management in the UK.
All three are prescription-only medicines requiring clinical assessment. Access through the NHS weight loss pathway involves referral to a tier 3 specialist service; private prescribing is also available through licensed UK prescribers.
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.
How to Access Weight Management Support in the UK
If you're interested in prescription weight loss options, start by speaking with your GP about whether you meet eligibility criteria based on your BMI and health conditions. Your GP can refer you to a local specialist weight management service (tier 3) for NHS assessment and treatment, though waiting lists vary by region. Alternatively, weight loss medication is available privately through online consultations with UK-licensed prescribers. Try our free GLP-1 weight loss calculator above to understand potential outcomes with licensed medications. Your GP remains the best source for personalised advice about which approach suits your health situation.
- 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.
Is topiramate licensed for weight loss in the UK?
No. Topiramate is not licensed for weight management in the UK — it is an anticonvulsant approved for epilepsy and migraine prevention. Any use for weight loss would be off-label and requires careful prescriber supervision. Licensed alternatives like Mounjaro and Wegovy are specifically approved for weight management and have robust clinical trial evidence.
What is the difference between licensed weight loss medications and off-label use?
Licensed medications (Mounjaro, Wegovy, Saxenda) have undergone rigorous clinical trials proving safety and efficacy for weight management and are approved by the MHRA. Off-label medications lack this specific approval for weight loss. Licensed options are safer, better-monitored, and represent the standard approach in UK medical practice.
How do I know if I'm eligible for prescription weight loss medication?
Eligibility typically 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 heart disease. South Asian, Chinese, Black African, and Black Caribbean adults may be eligible at slightly lower BMI thresholds. Your GP can assess your individual eligibility.
Can I access weight loss medication through the NHS?
Yes. NHS England has approved tirzepatide (Mounjaro) for use in specialist tier 3 weight management services. Access involves GP referral and specialist assessment. Availability and waiting times vary significantly by region. Private prescribing is also available if you do not wish to wait or use NHS services.
What is the safest way to lose weight in the UK?
The safest approach combines modest calorie reduction, increased physical activity, and professional support. For eligible adults, licensed weight loss medications can support this alongside lifestyle changes. Use our BMI calculator above to assess your current status, and speak with your GP about what weight management pathway suits your health needs and circumstances.
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.