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
How to Get an NHS Slimming Injection
Slimming injections, also known as weight loss injections or fat jabs, are prescription-only medications available through the NHS for eligible adults. Access depends on your BMI, health conditions, and location. This guide explains the NHS pathway, eligibility criteria, and how private options compare, so you can understand your options for prescription weight loss treatment.
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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.
Who Is Eligible for NHS Slimming Injections?
To access prescription slimming injections through the NHS, you must meet specific eligibility criteria. These are based on your BMI and whether you have weight-related health conditions:
- BMI of 30 or above (obesity), OR
- BMI of 27–29.9 (overweight) with at least one qualifying health condition
Qualifying weight-related conditions include type 2 diabetes, prediabetes, high blood pressure, abnormal blood fat levels, obstructive sleep apnoea, or history of heart attack or stroke. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds — eligibility may start at BMI 27.5 or above, as these groups face higher health risks at lower BMI levels. You must also be aged 18 or over, not pregnant or breastfeeding, and have no contraindications. Use our free BMI calculator to check where you currently stand against these thresholds.
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 Routes — How to Access Slimming Injections
NHS route: Request a referral from your GP to a specialist tier 3 weight management service. NHS weight loss injections are delivered through these specialist services, not standard GP prescription. Waiting times vary significantly by region (ICB) — some areas have waiting lists of several months to years. Access depends on local funding and service capacity.
Private route: Consult a UK-licensed prescriber online. If clinically appropriate, they issue a prescription dispensed by a GPhC-registered pharmacy. This is typically faster (days to weeks) and doesn't require NHS referral, but involves costs of £129–£320 monthly depending on dose. Both routes require assessment — your suitability for GLP-1 weight loss medication is evaluated individually. Try our GLP-1 weight loss calculator to estimate potential outcomes.
- 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 first step to get an NHS slimming injection?
Book an appointment with your GP and discuss weight management options. Mention that you want to be referred to a specialist weight management service. Your GP will assess your eligibility based on BMI and health conditions, then refer you to your local tier 3 service if appropriate.
How long does the NHS waiting list typically take?
Waiting times vary significantly by region. Some areas have waits of 3–6 months; others wait 12–24 months or longer. Contact your local integrated care board (ICB) to ask about current waiting times in your area, as capacity depends on local NHS funding.
Can I get a weight loss injection privately while waiting for the NHS?
Yes. You can access private prescription weight loss injections through online consultations with UK-licensed prescribers without waiting for NHS referral. Many people use private injections while on NHS waiting lists. Your GP should be informed of any medication you're taking.
What happens during an NHS or private weight loss consultation?
You'll be asked about your medical history, current medications, weight loss goals, and lifestyle. The prescriber will check your BMI, assess whether you have qualifying conditions, and discuss side effects and expectations. If approved, a prescription is issued. For private consultations, this typically happens online within 1–2 weeks.
Are slimming injections free on the NHS?
Yes, NHS slimming injections are free at point of care. However, accessing them depends on specialist service availability, eligibility criteria, and regional waiting lists. Private slimming injections cost between £129–£320 per month depending on the dose and provider.
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.