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
Free tracker included with every download this week
Methotrexate and Weight Loss — What You Need to Know
Methotrexate is a prescription medication used primarily to treat rheumatoid arthritis, psoriasis, and certain cancers — not for weight management. While some patients experience unintended weight changes on methotrexate, it is not prescribed for weight loss in the UK. If you are looking for effective weight management support, this guide explains the UK-licensed options available, how they work, and how to find out if you are eligible. Our free BMI calculator and weight loss projection tool can help you understand your current weight and explore your options.
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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 Medication Options
If you are looking for prescription weight loss medication in the UK, there are three licensed options available following a clinical assessment:
- Mounjaro (tirzepatide) — a once-weekly injectable that activates dual GIP and GLP-1 pathways. In clinical trials, participants lost an average of 15–21% of their body weight alongside diet and activity changes.
- Wegovy (semaglutide) — a once-weekly GLP-1 injection. Clinical trials showed average weight loss of around 15% of body weight.
- Saxenda (liraglutide) — a daily GLP-1 injection, offering another option for eligible adults.
These medications are available through NHS specialist weight management services or via private online prescribing. Individual results vary significantly, and all options work best alongside reduced-calorie diet and increased physical activity. Eligibility is assessed individually based on BMI and health conditions. Use our GLP-1 weight loss calculator to estimate potential outcomes at different doses.
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.
Eligibility, NHS Access, and Next Steps
To be eligible for prescription weight loss medication in the UK, you typically need a BMI of 30 or above, or 27–29.9 if you have weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Access through the NHS involves referral to a tier 3 specialist weight management service, though waiting lists vary significantly by region. Private access is available through online consultations with a UK-licensed prescriber without NHS referral.
Your first step is to speak with your GP about your weight management goals and ask whether you might be eligible for support. They can discuss your individual situation, explain what's available in your area, and refer you to specialist services if appropriate. Use our free BMI calculator to understand your current status, then have an informed conversation with your healthcare team about your options.
- 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.
Does methotrexate cause weight loss?
Methotrexate is not prescribed for weight loss. Some patients experience unintended weight changes whilst taking it for rheumatoid arthritis or cancer treatment, but this varies individually. If weight changes occur, discuss them with your GP — they may be related to the condition itself or other factors.
What is the most effective weight loss medication available in the UK?
Mounjaro and Wegovy are both UK-licensed for weight management. Clinical trials show Mounjaro may help achieve 15–21% average body weight loss, whilst Wegovy shows around 15% average loss. Individual results vary significantly. A prescriber will assess which is most suitable for your health profile.
How do I access weight loss injections on the NHS?
Weight loss injections are available through NHS specialist tier 3 weight management services. You need a referral from your GP. Eligibility requires BMI of 30 or above, or 27–29.9 with weight-related health conditions. Regional availability varies, and waiting lists can be lengthy in some areas.
Can I get weight loss medication privately without seeing my GP?
Yes. Private prescriptions are available through online consultations with UK-licensed prescribers without NHS referral. You will still need a clinical assessment to ensure the medication is safe and appropriate for you. Costs vary but typically range from £129–£320+ monthly depending on dose and provider.
What should I discuss with my GP about weight loss options?
Ask about your eligibility for weight loss medication, what's available locally through the NHS, typical waiting times, and whether private options are worth exploring for your situation. Mention any weight-related health conditions you have. Your GP can help you understand which approach suits your circumstances best.
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.