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
Over The Counter Weight Loss Pills in the UK
Over the counter weight loss pills are not available for weight management in the UK. Instead, eligible adults can access prescription weight management medication through the NHS or privately. If you're looking to lose weight, prescription options like Mounjaro and Wegovy have strong clinical evidence and can support significant weight loss alongside lifestyle changes. Your GP can assess whether you qualify based on your BMI and health profile.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Medication
The UK doesn't have over the counter weight loss pills, but three prescription medications are licensed for weight management:
- Mounjaro (tirzepatide) — a once-weekly injection with dual GIP and GLP-1 action. Clinical trials showed average weight loss of 15–21% of body weight.
- Wegovy (semaglutide) — a once-weekly GLP-1 injection. Average weight loss around 15% of body weight at the maximum dose.
- Saxenda (liraglutide) — a once-daily GLP-1 injection. Typically produces weight loss of 5–10% of body weight.
All three require a prescription following a clinical assessment. Individual results vary significantly. Weight management medications work best alongside a reduced-calorie diet and increased physical activity. Use our GLP-1 weight loss calculator above to estimate potential results 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.
Who Is Eligible for Prescription Weight Loss Medication in the UK?
To qualify for prescription weight loss medication on the NHS or through private assessment, you typically need:
- A BMI of 30 kg/m² or above, OR
- A BMI of 27–29.9 kg/m² with a weight-related health condition (diabetes, prediabetes, high blood pressure, cardiovascular disease, or sleep apnoea)
- Lower thresholds apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage
A GP or licensed prescriber will assess your individual health profile. Check your BMI using our free BMI calculator above, then speak to your GP about whether prescription weight loss medication is right for you. NHS access is through specialist weight management services; private access is available online following a clinical consultation.
- 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 there any weight loss pills available over the counter in the UK?
No. Weight loss medications are prescription-only in the UK. However, three medications are licensed for weight management: Mounjaro, Wegovy, and Saxenda. All require a prescription from a UK-licensed prescriber following a clinical assessment. Your GP can discuss eligibility or you can access private prescribing through accredited online services.
How much weight can you lose with prescription weight loss medication?
Clinical trials show significant variation. Mounjaro users lost on average 15–21% of their body weight. Wegovy achieved around 15% at the maximum dose. Saxenda typically produces 5–clinically studied weight loss. These results were achieved alongside reduced-calorie diet and exercise. Individual outcomes vary based on dose, adherence, and lifestyle factors.
What's the difference between Mounjaro and Wegovy?
Both are once-weekly injections but work differently. Mounjaro is a dual GIP and GLP-1 agonist (newer mechanism). Wegovy is a GLP-1 agonist only. Mounjaro starts at 2.5 mg and goes up to 15 mg. Wegovy starts at 0.25 mg and goes up to 2.4 mg. Both have strong clinical evidence. Your prescriber will help determine which is appropriate for you.
Can I get weight loss medication on the NHS?
Yes, but access is limited. You'll need referral to a specialist tier 3 weight management service by your GP. Eligibility depends on your BMI and health conditions. Waiting lists can be long in many regions. Private access is faster — prescription weight loss medication is available through GPhC-registered online prescribers following a consultation, typically costing £130–£300+ per month depending on dose.
Do I need to diet and exercise while taking weight loss medication?
Yes. Prescription weight loss medication is most effective alongside a reduced-calorie diet and regular physical activity. These medications support appetite control and help you feel fuller, but they're not a substitute for lifestyle changes. A balanced approach combining medication, nutrition, and movement produces the best long-term results. Track your progress with our free progress tracker.
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.