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 Slimming Injections on the NHS
Slimming injections—known as weight loss injections or GLP-1 medications—are now available through the NHS, but access requires understanding the eligibility criteria and referral pathway. If you're interested in prescription slimming injections, your GP can assess whether you qualify and refer you to specialist weight management services. This guide explains how the NHS route works, what the private route involves, and what to expect throughout the process.
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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 for NHS Weight Loss Injections
The NHS prescribes weight loss injections like Mounjaro (tirzepatide) and Wegovy (semaglutide) to adults meeting specific BMI and health criteria. You may qualify if you have a BMI of 30 or above, or a BMI of 27–29.9 with at least one weight-related health condition. Qualifying conditions include type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, obstructive sleep apnoea, or a history of cardiovascular disease.
If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recognises lower BMI thresholds due to higher health risks at lower weights—eligibility may begin at BMI 27.5 or above. You must also be aged 18 or over, not pregnant or breastfeeding, and have no contraindications. Use our free BMI calculator above to check your personal BMI and see where you fall within these criteria.
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 — Getting Slimming Injections
NHS Route: Ask your GP for a referral to a tier 3 specialist weight management service. The GP will assess your eligibility and refer you if appropriate. Waiting times vary significantly by region (ICB) and can range from weeks to over a year in some areas. Once accepted into the service, you'll have multidisciplinary support including dietitians and behavioural specialists.
Private Route: Book an online consultation with a UK-licensed prescriber through a GPhC-registered pharmacy. The assessment happens within days, and if approved, your prescription is dispensed without NHS waiting lists. Private costs typically range from £129–£320 monthly depending on medication and dose. Both routes require a clinical assessment—nhs weight loss injections or private prescriptions are never available without one.
- 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's the difference between NHS and private slimming injections?
NHS slimming injections are prescribed through specialist tier 3 services following GP referral, often with longer waiting times but multidisciplinary support included. Private weight loss injections are accessed via online consultation with a licensed prescriber and dispensed by a pharmacy, typically faster but at a cost. Both require clinical assessment and are prescription-only medicines.
How long does it take to get slimming injections on the NHS?
NHS waiting times vary significantly by region. Some areas offer appointments within weeks; others have waiting lists of several months to over a year. Private online consultations are usually completed within 2–5 days. Contact your local ICB or specialist weight management service for current waiting times in your area.
Do I need to be overweight to qualify for weight loss injections?
No. You need a BMI of 30 or above, or 27–29.9 with a weight-related health condition (diabetes, high blood pressure, sleep apnoea, etc.). Lower BMI thresholds apply for people of South Asian, Chinese, Black African, or Black Caribbean heritage. Your GP or prescriber will assess your individual eligibility.
What happens during the NHS assessment for slimming injections?
Your GP will review your medical history, current medications, and weight-related health conditions. If eligible, you'll be referred to a specialist tier 3 service. There you'll have consultations with dietitians, a prescriber, and possibly a psychologist. They'll discuss diet, exercise, and medication options before prescribing begins.
Can I use our weight loss calculator to estimate results before getting slimming injections?
Yes. Our free GLP-1 weight loss calculator allows you to explore projected weight loss at different doses of Mounjaro or Wegovy. This gives you a realistic sense of potential outcomes based on clinical trial data, though individual results vary. Discuss these projections with your GP or prescriber.
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.