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 Fat Injections for Weight Loss in the UK
Fat injections—commonly called slimming injections or weight loss jabs—are prescription-only medicines available in the UK through two routes: the NHS and private prescribing services. These GLP-1 weight loss injections work by helping regulate appetite and support feeling fuller after meals. Access depends on meeting eligibility criteria based on your BMI and health conditions. This guide explains how to get prescription slimming injections, what the assessment process involves, and the key differences between NHS and private access.
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.
Who is Eligible for Weight Loss Injections in the UK?
To access weight loss injection eligibility in the UK, you must meet NHS-aligned 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 cholesterol levels, obstructive sleep apnoea, or history of heart attack or stroke. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower thresholds apply: BMI 27.5 or above may qualify, due to higher cardiovascular risk at lower weights. Use our free BMI calculator above to check your BMI instantly. You cannot access these medications if you are under 18, pregnant, planning pregnancy, or breastfeeding. A licensed prescriber will assess your individual health during a clinical consultation.
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 to Access: NHS vs Private
NHS Route: Your GP refers you to a tier 3 specialist weight management service. These services provide comprehensive assessment, prescription, and ongoing support—but waiting lists vary significantly by region, sometimes stretching months to years. Private Route: You can access private weight loss injections through GPhC-registered online pharmacies. A UK-licensed prescriber conducts a consultation (usually online), assesses your eligibility, and issues a prescription if appropriate. Private access is typically faster, but costs range from £129–£320 monthly depending on dose. Both routes require a clinical assessment—weight loss injections are never supplied without one. Our GLP-1 weight loss calculator can help you understand projected outcomes once you're prescribed.
- 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 happens during a weight loss injection consultation?
A prescriber will review your medical history, current medications, BMI, and weight-related health conditions. They may ask about previous weight loss attempts, lifestyle, and health goals. If you're eligible, they'll explain how the medication works, potential side effects, and what to expect. This assessment ensures the medication is safe and appropriate for you individually.
Can I get weight loss injections on the NHS without a waiting list?
NHS access depends on your local integrated care board (ICB) and regional specialist services. Many areas have significant waiting lists. If you need faster access, private prescribing services offer quicker routes, though at a cost. Ask your GP about waiting times in your area.
What's the difference between fat jabs and other slimming injections?
"Fat jabs," "slimming injections," and "weight loss jabs" are all colloquial terms for the same type of medication—GLP-1 receptor agonists or GIP/GLP-1 agonists. They're prescription-only medicines, not cosmetic injections. They work by reducing appetite, not dissolving fat directly.
Do I need to pay for weight loss injections privately?
NHS access is free if available through your local tier 3 service, though access is limited and variable. Private prescribing typically costs £129–£320 monthly depending on dose and provider. Some private services offer payment plans. Always check what's included—medication, follow-up consultations, and support vary.
What if I'm not eligible for weight loss injections?
If you don't meet BMI or health condition criteria, your GP may recommend other tier 1 or tier 2 weight management support—such as digital programmes, behaviour change services, or community weight loss groups. Use our BMI calculator and weight converter to track your progress toward eligibility, or discuss alternatives with your GP.
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.