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
Cheap Weight Loss Pills in the UK
Weight loss pills in the UK are prescription-only medicines that require a clinical assessment before being dispensed. The cost varies significantly depending on whether you access treatment through the NHS or privately, and which medication you're prescribed. Understanding your options for prescription weight loss medication, NHS eligibility, and realistic costs can help you make informed decisions about weight management 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.
Types of Prescription Weight Loss Medication Available
The UK's main prescription weight loss options are GLP-1 receptor agonist injections and dual GIP/GLP-1 medications. These work by reducing appetite and supporting feeling fuller after smaller meals.
- Mounjaro (tirzepatide) — once-weekly injection, £129–£320 per month privately, available through NHS specialist services
- Wegovy (semaglutide) — once-weekly injection, similar private costs, NHS access varies by region
- Saxenda (liraglutide) — daily injection, typically the most affordable private option at lower doses
These are not traditional "pills" but injectable medications. All require prescription-only access following a clinical assessment. Individual results vary, and weight loss medication is typically used alongside dietary changes and increased physical activity for weight management UK adults.
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.
NHS vs Private Access and Cost
Access through the NHS is free once prescribed, but involves referral to a specialist tier 3 weight management service and can have waiting lists of weeks to months depending on your region. Private prescribing through a GPhC-registered online pharmacy typically costs £129–£320 per month depending on medication and dose, with no waiting list.
Try our free GLP-1 weight loss calculator to explore potential outcomes at different doses. Cost effectiveness depends on your BMI, health conditions, and personal circumstances. Use our BMI calculator to check your eligibility for weight management support.
Prescription weight loss medication is not "cheap" compared to unregulated supplements, but it is evidence-based. Clinical trials show GLP-1 medications may help achieve 14–clinically studied weight loss on average. The NHS recommends losing no more than 0.5–1 kg per week sustainably. Before starting any prescription weight loss pill or injection, your prescriber will assess whether you meet eligibility criteria: BMI 30+ or BMI 27+ with weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea.
- 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 cheap weight loss pills available over the counter in the UK?
No. All licensed weight loss medications in the UK are prescription-only and require a clinical assessment from a UK-licensed prescriber. Unregulated or unproven supplements sold as "cheap weight loss pills" are not monitored by the MHRA and may be unsafe. Always consult your GP or a registered healthcare professional.
What is the cheapest weight loss medication available in the UK?
Saxenda (liraglutide) is typically the most affordable prescription option at lower doses, starting around £129 per month privately. Mounjaro and Wegovy cost similarly at maintenance doses. NHS access is free but requires specialist referral. Prices vary by provider and dose escalation.
Can I get weight loss pills free on the NHS?
Yes. If your GP refers you to a tier 3 specialist weight management service and you meet eligibility criteria (BMI 30+ or BMI 27+ with comorbidities), prescription weight loss medication is free on the NHS. However, waiting times vary significantly by region — some areas have waiting lists of several months.
How much weight can I expect to lose with prescription weight loss medication?
Clinical trials show GLP-1 medications may help achieve 14–clinically studied weight loss on average over 68–72 weeks, alongside a reduced-calorie diet and physical activity. Individual results vary significantly. Our weight loss calculator can estimate potential outcomes at different doses based on your current weight and height.
What is the difference between Mounjaro and Wegovy for weight loss?
Both are prescription-only once-weekly injections. Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials suggest similar average weight loss outcomes (15–21% for Mounjaro, 14–15% for Wegovy), but individual results vary. Your prescriber will assess which is appropriate for you.
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.