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
Who Qualifies for Weight Loss Injections in the UK?
Weight loss injections are prescription-only medicines available to eligible UK adults. To access prescription weight loss medication like Wegovy or Mounjaro, you must meet specific BMI and health criteria set by the NHS and private prescribers. These criteria are designed to ensure the medication is appropriate for your individual health situation. Eligibility varies depending on whether you're accessing treatment through the NHS or privately, and your ethnicity may also affect the thresholds used. This guide explains exactly who qualifies and how to check if you might be eligible.
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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.
BMI Thresholds and Eligibility Requirements
The primary criteria for weight loss injections in the UK is based on your BMI (body mass index). Use our free BMI calculator above to check your current BMI instantly.
For most UK adults, you may be eligible for prescription weight loss medication if you:
- Have a BMI of 30 kg/m² or above (classified as obese), OR
- Have a BMI of 27–29.9 kg/m² (classified as overweight) AND have at least one weight-related health condition
However, for adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds:
- BMI of 27.5 kg/m² or above (without additional health conditions), OR
- BMI of 23 kg/m² or above with weight-related health conditions
These lower thresholds reflect higher cardiovascular and metabolic disease risk in these populations at lower BMI levels. Your GP or prescriber will discuss which thresholds apply to you based on your background.
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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.
Weight-Related Health Conditions That May Qualify
If your BMI falls between 27–29.9 kg/m², you may still qualify for weight loss medication if you have one or more weight-related health conditions. These include:
- Type 2 diabetes or prediabetes
- High blood pressure (hypertension)
- High cholesterol or abnormal blood fats (dyslipidaemia)
- Obstructive sleep apnoea
- History of heart attack, stroke, or cardiovascular disease
- Non-alcoholic fatty liver disease
If you have any of these conditions, calculate your BMI using our free tool and discuss your weight management with your GP. They can assess whether prescription medication alongside lifestyle changes might be appropriate for you.
- 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 minimum BMI for weight loss injections in the UK?
For most UK adults, the minimum BMI is 30 kg/m² without additional health conditions. If you have weight-related conditions like type 2 diabetes or high blood pressure, eligibility may start at BMI 27 kg/m². For South Asian, Chinese, Black African, or Black Caribbean adults, thresholds are lower (from BMI 23 with conditions). Use our BMI calculator above to check your current BMI.
Can I get weight loss injections on the NHS?
Weight loss injections are available through NHS specialist tier 3 and tier 4 weight management services, but access varies significantly by region. Your GP can refer you to your local specialist service if you meet eligibility criteria, but waiting times can be several months or longer. Many people access these medications privately through online consultations with UK-licensed prescribers.
Do I need a health condition to qualify, or is BMI alone enough?
BMI alone is enough if your BMI is 30 or above. If your BMI is between 27–29.9 (overweight category), you'll need at least one weight-related health condition to qualify. Examples include type 2 diabetes, high blood pressure, sleep apnoea, or previous heart disease. Your GP can advise whether your specific conditions qualify.
Does ethnicity affect weight loss injection eligibility?
Yes. The NHS recognises that people of South Asian, Chinese, Black African, and Black Caribbean heritage have higher health risks at lower BMI levels. These groups may qualify for weight loss medication starting at BMI 23–27.5 kg/m², whereas the general population threshold is BMI 27–30. Always inform your prescriber of your ethnic background.
What happens after I'm assessed as eligible?
If you're approved, a prescriber will choose an appropriate GLP-1 medication (such as Wegovy or Mounjaro) and start you on the lowest dose. You'll be monitored regularly to check how well the medication is working and whether you need any dose adjustments. Weight loss medication works best alongside reduced-calorie diet and increased physical activity. Our free GLP-1 weight loss calculator can help you project potential results.
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.