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 Companies in the UK — Your Prescription Options
If you're looking at weight loss companies in the UK, you'll find options range from NHS services to private prescribing platforms. The most significant development in recent years has been the availability of prescription weight management medications — specifically GLP-1 receptor agonists and dual GIP/GLP-1 injections. These are available through both NHS specialist services and private online prescribing, depending on your eligibility and circumstances. This guide explains how UK weight management works and what prescription options are available to you.
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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 Medications
Three prescription-only medications are currently licensed in the UK for weight management. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist administered as a once-weekly injection, with clinical trials showing average weight loss of approximately 15–21% of body weight. Wegovy (semaglutide) is a GLP-1 receptor agonist also given once weekly, with average weight loss around 15% in clinical trials. Saxenda (liraglutide) is an older GLP-1 injection given daily rather than weekly.
- Mounjaro: doses from 2.5 mg to 15 mg weekly
- Wegovy: doses from 0.25 mg to 2.4 mg weekly
- Saxenda: doses from 0.6 mg to 3 mg daily
All are prescription-only medicines requiring clinical assessment. Individual results vary significantly, and weight loss medication works best alongside dietary changes and increased physical activity. Use our free GLP-1 weight loss calculator to estimate potential outcomes 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.
NHS vs Private: How to Access Weight Loss Medication in the UK
NHS access: NICE has approved tirzepatide (Mounjaro) for use within NHS specialist weight management services. Referral comes through your GP to a tier 3 or tier 4 weight management service. NHS availability varies significantly by region, and waiting lists can be lengthy in many areas.
Private access: GLP-1 medication is available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. This route does not require NHS referral. Costs typically range from £129–£320 monthly depending on dose and provider.
To explore your options, start by discussing weight management with your GP — they can assess your eligibility and discuss both NHS and private pathways. Check your BMI using our free BMI calculator to understand where you stand relative to NHS eligibility thresholds.
- 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 is the difference between Mounjaro and Wegovy?
Both are once-weekly injections for weight management, but Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist, while Wegovy (semaglutide) activates only the GLP-1 pathway. Mounjaro typically produces slightly higher average weight loss (15–21% vs 15%) in clinical trials, but individual results vary considerably. Your prescriber will recommend the most suitable option for you.
Am I eligible for prescription weight loss medication on the NHS?
NHS eligibility typically includes adults with a BMI of 30 or above, or 25–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or heart disease. South Asian and Black African heritage adults may have lower thresholds. Your GP can assess your individual eligibility and refer you to specialist services.
How much does GLP-1 weight loss medication cost privately in the UK?
Private prescription weight loss medication typically costs £129–£320 per month, depending on the drug, dose, and provider. This is in addition to the cost of the clinical assessment. Costs can vary, so it's worth comparing providers. NHS access is free but involves specialist referral and may involve waiting lists.
How quickly will I lose weight on prescription weight loss medication?
Clinical trials show average weight loss of 0.5–1 kg per week on GLP-1 medications, though individual results vary significantly. Some people lose more, some less. Medication works best alongside a reduced-calorie diet and increased physical activity. Use our weight loss calculator to see projected timelines based on dose and your starting weight.
Do I need to use our weight converter or BMI calculator to check my eligibility?
Yes — our free weight converter and BMI calculator can help you understand where you stand relative to NHS thresholds. If you're unsure of your weight in kg or your BMI, these tools provide instant calculations. However, only a healthcare professional can formally assess your eligibility for prescription 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.