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 in the UK — Your Complete Options Guide
If you're looking for pills to lose weight in the UK, you have several options available to you — from lifestyle-based approaches right through to prescription medications. The NHS offers free weight loss support through different tiers of service, while prescription weight loss pills like Mounjaro and Wegovy are available through both NHS specialist services and private prescribing. This guide covers all the main approaches to help you understand what's available and how to access sustainable weight loss support 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.
Weight Loss Options Available in the UK
The UK healthcare system offers a structured approach to weight loss support through several tiers. Tier 1 includes free self-help resources, digital tools, and community programmes you can access directly without a GP referral. Tier 2 involves primary care support — your GP can refer you to evidence-based behaviour change programmes like the NHS Weight Loss Plan.
Tier 3 is where prescription weight loss medication becomes available. This is specialist services accessed through your GP, where medicines like Mounjaro (tirzepatide) and Wegovy (semaglutide) may be prescribed alongside lifestyle support. Use our free GLP-1 weight loss calculator to explore how these medicines work and what results clinical trials have shown.
Tier 4 covers bariatric surgery for severe obesity with serious health complications. Most people benefit from starting at Tier 1 or 2 and stepping up if needed. Each approach can support sustainable weight loss 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.
Choosing the Right Weight Loss Approach for You
The best weight loss method depends on your personal circumstances, BMI, health conditions, motivation, and access to support. Use our free BMI calculator to understand where you currently sit on the NHS health scale — this helps determine what tier of support you may be eligible for.
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, you may be eligible for prescription weight loss support. Start by speaking with your GP, who can assess your individual situation and refer you to the right service. Private options are also available through online prescribing if you prefer faster access without waiting lists.
- 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.
Are weight loss pills available on the NHS in the UK?
Yes. The NHS offers prescription weight loss medicines like Mounjaro and Wegovy through specialist tier 3 weight management services. Eligibility is based on your BMI and health conditions. You'll need a GP referral to access these services. Access and waiting times vary significantly by region. Private prescribing is also available without NHS referral.
What are the main prescription weight loss pills available in the UK?
The main prescription weight loss pills in the UK are Mounjaro (tirzepatide), a dual GIP/GLP-1 receptor agonist, and Wegovy (semaglutide), a GLP-1 receptor agonist. Saxenda (liraglutide) is also licensed but is injected daily rather than weekly. All three are prescription-only and require clinical assessment before being prescribed.
How effective are weight loss pills for losing weight?
Clinical trials show that GLP-1 medicines help participants lose an average of 15–21% of their body weight alongside lifestyle changes. Individual results vary significantly. Weight loss pills work best when combined with a reduced-calorie diet and increased physical activity. They're not a standalone solution but a tool to support your overall weight management approach.
What should I do if I want to explore weight loss pills?
Start by speaking with your GP, who can assess your eligibility and discuss the options available to you. If you're registered with the NHS, your GP can refer you to specialist weight management services. You can also explore private prescribing options through accredited online services if you want faster access.
Are there free weight loss options available before trying pills?
Yes. The NHS offers free tier 1 and tier 2 support including digital tools, community programmes, and GP-led behaviour change interventions. Track your progress with our free progress tracker to monitor your weight loss journey. Many people achieve sustainable results through lifestyle changes alone before considering medication.
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.