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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Over-the-Counter Weight Loss Pills in the UK
If you're searching for over-the-counter weight loss pills, it's worth knowing that most available without prescription have limited scientific evidence. However, the UK does have access to clinically proven prescription weight management options. Whether you're looking to lose weight or interested in weight management UK options, this guide explains what's available, how NHS weight loss support works, and what prescription alternatives may be suitable for eligible adults.
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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.
Prescription Weight Loss Options Available in the UK
Rather than relying on unproven OTC supplements, the NHS and private prescribers in the UK can offer three licensed prescription weight loss medications with clinical evidence behind them:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist, injected once weekly. In clinical trials, participants lost an average of 15–21% of their body weight over 72 weeks.
- Wegovy (semaglutide) — a GLP-1 receptor agonist, injected once weekly. Clinical data showed average weight loss of approximately 15% of body weight.
- Saxenda (liraglutide) — a GLP-1 receptor agonist, injected daily. Typically used when weekly options aren't suitable.
These are prescription-only medicines requiring a clinical assessment. Unlike unregulated OTC pills, they're approved by the MHRA and supported by rigorous clinical trials. All work best alongside a reduced-calorie diet and increased physical activity. Use our free GLP-1 weight loss calculator to estimate potential results at different doses, and check your BMI with our BMI calculator to see if you may be eligible.
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.
How to Access Prescription Weight Loss Treatment in the UK
Eligibility for prescription weight loss medication typically requires a BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. Access routes differ:
- NHS route: Speak to your GP about referral to a tier 3 specialist weight management service. Availability and waiting times vary significantly by region.
- Private route: Consult with a UK-licensed prescriber through an online service. Assessment and prescription typically happen within days if you're eligible.
Your GP is the best starting point to discuss your individual situation, explore prescription weight loss options, and understand what support is available through NHS weight loss services. They can also discuss whether medication is right for you based on your health, medications, and weight loss goals.
- 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 OTC weight loss pills effective in the UK?
Most over-the-counter weight loss pills lack strong clinical evidence. The UK's MHRA has approved only three prescription weight loss medications with proven efficacy: Mounjaro, Wegovy, and Saxenda. These require a prescription and clinical assessment. OTC supplements are often unregulated and their weight loss effects are typically modest or unproven.
What is the difference between OTC pills and prescription weight loss medication?
Prescription weight loss medications like Mounjaro and Wegovy are licensed by the MHRA, backed by clinical trials, and prescribed following a proper health assessment. OTC pills are typically unregulated supplements with limited evidence. Prescription options are significantly more effective — averaging 15–clinically studied weight loss in trials compared to minimal results from most OTC products.
How do I know if I'm eligible for prescription weight loss treatment?
You may be eligible if you have a BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure. Speak to your GP for a formal assessment. Our BMI calculator can help you check your current BMI and understand where you stand relative to NHS thresholds.
Can I get prescription weight loss medication through the NHS?
Yes, prescription weight loss medications are available through NHS specialist tier 3 weight management services. You'll need a GP referral. Availability and waiting times vary by region. Private prescribing is also available through UK-licensed online prescribers, often with shorter wait times but at a cost.
What should I do first if I want to lose weight?
Start by speaking to your GP. They can assess your health, discuss whether prescription medication is appropriate, and explain available options — whether NHS services or private alternatives. Track your progress using our free progress tracker, and use our weight management UK resources to understand your BMI, eligibility, and realistic expectations.
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.