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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How to Get Slimming Jabs on the NHS
Slimming jabs — also called weight loss injections, fat jabs, or GLP-1 weight loss medications — are now available in the UK through both the NHS and private providers. The most commonly prescribed options are Mounjaro (tirzepatide) and Wegovy (semaglutide). If you're considering whether you're eligible and how to access them, this guide explains the NHS pathway, eligibility criteria, and what to expect. Your route depends on your BMI, health conditions, and whether you choose NHS or private access.
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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.
Eligibility Criteria for Weight Loss Injections
To access slimming injections through the NHS or private providers, you must meet specific eligibility criteria:
- BMI of 30 or above (obesity), 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 cardiovascular disease history.
Ethnicity adjustments: If you are of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds — you may be eligible starting at BMI 27.5 or above, as these groups face higher health risks at lower weights.
Check your BMI using our free BMI calculator above — it takes seconds and shows you instantly where you stand against NHS thresholds. Those under 18, pregnant, breastfeeding, or with certain medical conditions are not 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.
Two Routes: NHS vs Private Access
NHS Route: You'll need a GP referral to a specialist tier 3 weight management service. Your GP assesses your eligibility, then refers you to your local service. Waiting times vary significantly by region — some areas have waits of several months or longer. Once assessed by the specialist team, prescription slimming injections may be offered alongside dietary and lifestyle support.
Private Route: You can access weight loss injections through GPhC-registered online providers. You'll complete an online consultation with a UK-licensed prescriber, who assesses your suitability. If approved, your prescription is dispensed by a regulated pharmacy. This route is faster — typically days rather than months — but involves a private cost (usually £129–£320 per month depending on dose).
Try our GLP-1 weight loss calculator to explore projected outcomes at different doses before consulting.
- 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.
How long does the NHS referral process take?
Waiting times vary significantly by region and local NHS capacity. Some specialist services have waiting lists of 6–12 months or longer. Initial GP appointment can be booked within 2–4 weeks. Once referred, you'll be contacted by your local specialist weight management service to arrange assessment. Private access is typically faster, with consultation and prescription within days.
What happens at an NHS specialist weight management consultation?
The specialist team assesses your medical history, current medications, BMI, and weight-related conditions. They'll discuss lifestyle changes, dietary support, and whether prescription weight loss injections are appropriate. They'll review side effects and explain how the medication works. If approved, you'll receive a prescription and training on self-injection, then begin treatment with regular monitoring.
Can I get slimming jabs without seeing a GP first?
Through the NHS, you need a GP referral to access specialist services. Privately, you can access online consultations directly without a GP referral — an online prescriber assesses your eligibility based on your health information. Both routes require a clinical assessment before prescription. The private route bypasses the NHS waiting list but involves a private cost.
What's the difference between NHS and private slimming jabs?
The medication itself is identical — Mounjaro or Wegovy. The difference is the pathway: NHS involves GP referral and specialist assessment (free but may involve longer waits), while private involves online consultation and prescription from a regulated pharmacy (faster but costs £129–£320/month). Both require proper clinical assessment and medical supervision.
Are weight loss injections like Mounjaro and Wegovy available on the NHS?
Yes. NICE has approved tirzepatide (Mounjaro) and semaglutide (Wegovy) for use in NHS specialist weight management services. However, availability varies significantly by region and local funding. Many NHS areas have limited capacity or long waiting lists. Private access is widely available through regulated online providers without waiting lists, though at personal cost.
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.