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 and Medication Options in the UK
If you're looking for weight loss pills in the UK, you have several evidence-based options available to you. The approach that's right for you depends on your BMI, health conditions, lifestyle, and personal circumstances. This guide covers everything from free NHS weight loss support to prescription medications, helping you understand what's available and how to access it. Use our free BMI calculator above to establish your starting point before exploring 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.
Weight Loss Approaches Available in the UK
Weight loss in the UK is typically structured as a four-tier pathway. Tier 1 includes self-help tools, digital programmes, and community weight loss support — all free and available without a GP referral. Tier 2 involves primary care interventions through your GP, including behaviour change programmes and structured weight loss plans. Tier 3 is specialist NHS weight management services, where prescription medications may be considered. Tier 4 covers bariatric (weight loss) surgery for severe obesity.
Prescription weight loss medications available in the UK include GLP-1 receptor agonists like Wegovy (semaglutide) and dual GIP/GLP-1 agonists like Mounjaro (tirzepatide). These are prescription-only medicines requiring clinical assessment. They are typically prescribed alongside dietary changes and increased physical activity, not as a replacement for lifestyle changes. Access through the NHS is via tier 3 specialist services, though waiting lists vary significantly by region. Private access is also available through licensed UK prescribers.
Eligibility for prescription weight loss medication typically requires 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 cardiovascular disease. Your GP can assess whether prescription treatment is appropriate for you. Try our free GLP-1 weight loss calculator to understand potential outcomes if you're considering this route.
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.
Choosing the Right Weight Loss Approach for You
The best weight loss approach is one you can sustain long-term. Consider starting with tier 1 support — the NHS Weight Loss Plan, digital tools like MyWeightCheck, and local community programmes are free and effective for many people. Safe, sustainable weight loss is typically 0.5–1 kg per week and focuses on creating a calorie deficit through balanced diet and physical activity.
If you've tried lifestyle changes alone without success, or if you have weight-related health conditions, discuss prescription medication options with your GP. They can assess your individual circumstances, explain how each medication works, and discuss potential side effects. Track your progress with our free progress tracker to monitor what's working for you. Your GP can also refer you to tier 3 specialist services if needed, where you'll receive multidisciplinary support including dietitians, psychologists, and weight management specialists.
- 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 weight loss pills are available on the NHS?
The NHS prescribes GLP-1 medications (like Wegovy) and GIP/GLP-1 medications (like Mounjaro) for eligible adults through specialist tier 3 weight management services. Access is typically via GP referral. NHS availability varies by region and waiting lists can be lengthy. Your GP can assess your eligibility and explain local pathways.
Can I get weight loss pills privately in the UK?
Yes. Prescription weight loss medications are available through private online prescribing services following a clinical assessment from a UK-licensed prescriber. These are dispensed by GPhC-registered pharmacies. Costs vary by medication and dose but typically range from £129–£320 monthly. You don't need NHS referral for private access.
How effective are weight loss pills?
Clinical trials show GLP-1 medications help most people lose an average of 15% body weight, though individual results vary significantly. Effectiveness increases when combined with dietary changes and physical activity. Weight loss typically begins within weeks and continues over months. Results depend on the dose, your adherence, and your lifestyle changes.
Are weight loss pills safe long-term?
Prescription weight loss medications approved in the UK have been tested for safety through rigorous clinical trials. Common side effects include nausea and digestive changes, usually mild and temporary. Some conditions may make them unsuitable — your prescriber will assess this. Always discuss concerns with your GP or prescriber.
What should I do before asking my GP about weight loss pills?
First, calculate your BMI using our free BMI calculator to establish your starting point. Document any weight-related health conditions (diabetes, high blood pressure, sleep apnoea). Try NHS tier 1 support (Weight Loss Plan, digital tools) if you haven't already. Then discuss with your GP, who can assess whether medication is appropriate for you and refer you to specialist services if needed.
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.