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 Pills From Your GP — What's Available in the UK
If you're looking for weight loss pills from your GP, there are now several prescription-only options available in the UK. These medications can support weight management when used alongside a reduced-calorie diet and increased physical activity. Your eligibility depends on your BMI and overall health. This guide explains the prescription weight loss options available through the NHS and privately, who can use them, and how to have the conversation with your GP about whether medication might be right for you.
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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 Prescription Weight Loss Medications
Three main prescription weight loss medications are currently licensed in the UK:
- Mounjaro (tirzepatide) — A once-weekly injection that activates dual GIP and GLP-1 hormone pathways. In clinical trials, it helped participants lose an average of 15–21% of their body weight over 72 weeks, though individual results vary significantly.
- Wegovy (semaglutide) — A once-weekly GLP-1 injection. Clinical trial data showed an average weight loss of around 15% of body weight, used alongside lifestyle changes.
- Saxenda (liraglutide) — A once-daily GLP-1 injection. Less commonly prescribed in recent years but still available. Requires daily administration rather than weekly.
All three are prescription-only medicines and require a clinical assessment before your GP or a prescriber can offer them. They work best when combined with dietary changes and exercise. Use our GLP-1 weight loss calculator to see potential projected weight loss at different dose levels, and our BMI calculator to check your starting point.
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 and How to Access Weight Loss Medication From Your GP
To be eligible for prescription weight loss medication in the UK, you generally need:
- A BMI of 30 or above, OR
- A BMI of 27–29.9 with at least one weight-related health condition (such as type 2 diabetes, prediabetes, high blood pressure, or sleep apnoea)
- For people of South Asian, Chinese, Black African, or Black Caribbean heritage, lower thresholds may apply (from BMI 27.5)
On the NHS, weight loss medication is typically prescribed through specialist tier 3 weight management services, not standard GP practice. You'll need a referral from your GP, though waiting lists vary by region. Alternatively, prescription weight loss medication is available privately through online consultations with UK-licensed prescribers. Either route requires a clinical assessment to confirm suitability.
- 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.
Can my GP prescribe weight loss pills directly?
On the NHS, weight loss medication is typically prescribed by specialist tier 3 weight management services rather than standard GP practices. Your GP can refer you to these services, but they cannot usually prescribe directly. Waiting lists vary significantly by region. Privately, you can access prescription weight loss medication through an online consultation with a UK-licensed prescriber without an NHS referral.
How much weight can I expect to lose with prescription weight loss pills?
Clinical trials show average weight loss of 15–21% of body weight with Mounjaro and around 15% with Wegovy, though individual results vary considerably. These averages are achieved alongside reduced-calorie diet and increased physical activity. Your personal results will depend on your starting weight, lifestyle changes, dose, and how your body responds to the medication.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) activates only the GLP-1pathway. Both are once-weekly injections. Mounjaro has shown slightly higher average weight loss in trials, but both are effective. Your prescriber will assess which is more appropriate for your individual health profile.
Are weight loss pills on the NHS free?
If prescribed through the NHS specialist weight management service, weight loss medication is free on prescription. However, NHS access is limited and varies by region, with long waiting lists in many areas. Private prescribing costs typically range from £129–£320 per month depending on the medication and dose.
What should I ask my GP about weight loss medication?
Ask your GP whether you might be eligible for prescription weight loss support, how to access NHS services in your area, typical waiting times, and what the referral process involves. You can also discuss private options. Use our BMI calculator to have an informed conversation about where your weight currently sits and what support might help. Bring up any relevant health conditions like diabetes or high blood pressure.
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.