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
Fat Jabs Cost and How to Access Weight Loss Injections in the UK
Fat jabs (weight loss injections) are now widely available in the UK through both NHS and private routes. The cost varies significantly depending on the medication, dose, and where you access treatment—ranging from NHS-funded access (depending on your area) to private prescriptions costing £129–£320 per month. Understanding your eligibility and the two main pathways to getting slimming injections can help you make an informed decision about whether this treatment is right for you. Our free GLP-1 weight loss calculator can help you estimate potential results at different doses.
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.
Eligibility Criteria for Weight Loss Injections
To access prescription slimming injections in the UK, you must meet specific eligibility criteria based on your BMI and health conditions. The standard thresholds are:
- BMI of 30 or above (obese category), OR
- BMI of 27–29.9 (overweight) with at least one weight-related health condition
Weight-related conditions that may qualify include type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, obstructive sleep apnoea, or history of heart attack or stroke. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds—eligibility may start at BMI 27.5 or above, because these groups face higher health risks at lower BMI levels. You cannot access weight loss injections if you are under 18, pregnant, breastfeeding, or have a known allergy to the medication. A prescriber will assess your individual circumstances during a clinical consultation to determine suitability. Check your personal BMI using our free BMI calculator above to see where you stand.
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: Cost and Access Routes
NHS route: Prescription weight loss injections may be available through NHS specialist tier 3 weight management services. Access requires referral from your GP, and availability varies significantly by region (ICB area). Waiting lists can be lengthy—sometimes many months or over a year. When available, NHS-prescribed medications are dispensed at standard prescription cost (£9.90 per item in England if eligible for free prescriptions, or free if you qualify). Private route: Available through GPhC-registered online pharmacies, typically costing £129–£320 per month depending on dose. Private consultations are faster (often within days), don't require NHS referral, and medication is posted directly to you. Both routes require a valid prescription from a UK-licensed prescriber following a clinical assessment. Track your weight loss progress once treatment begins using our free progress tracker.
- 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 do fat jabs cost in the UK?
Private weight loss injections typically cost £129–£320 per month depending on the medication and dose. Mounjaro and Wegovy are more expensive at higher doses. NHS-prescribed injections cost £9.90 per item in England (or free if you qualify for free prescriptions), but availability varies by region and waiting lists can be very long.
Can I get slimming injections on the NHS?
Yes, weight loss injections are available on the NHS through specialist tier 3 weight management services, but only after GP referral and assessment. Availability depends on your ICB area—some regions have very limited access. Waiting lists are often months to over a year. Private access is faster and doesn't require NHS referral.
What medications are available as fat jabs in the UK?
Three medications are UK-licensed for weight management: Mounjaro (tirzepatide, dual GIP/GLP-1), Wegovy (semaglutide, GLP-1), and Saxenda (liraglutide, GLP-1). Mounjaro and Wegovy are once-weekly injections. Saxenda is a daily injection. All require prescription and clinical assessment.
How quickly can I get a private prescription for slimming injections?
Private online consultations typically take 1–7 days from booking to prescription issue. Once prescribed, medication is usually dispatched within 1–3 working days. This is significantly faster than NHS routes, which involve GP referral and specialist waiting lists of weeks to months.
Do I need my GP's permission to get private slimming injections?
No. Private prescriptions from UK-licensed prescribers do not require GP permission or involvement. However, it's good practice to inform your GP that you're starting weight loss treatment so they can monitor your health and adjust any other medications if needed.
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.