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
What's the Minimum BMI for Mounjaro in the UK?
In the UK, the minimum BMI for Mounjaro eligibility is 30 kg/m² for adults without weight-related health conditions. However, if you have conditions like type 2 diabetes, high blood pressure, or heart disease, you may be eligible at a BMI of 27–29.9 kg/m². For people of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds apply due to higher health risks at lower weights. Your GP or a licensed prescriber will assess your individual eligibility following a clinical assessment.
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.
BMI Eligibility Ranges for Mounjaro
Standard BMI thresholds for Mounjaro eligibility in the UK:
- BMI 30 kg/m² or above — eligible regardless of health conditions
- BMI 27–29.9 kg/m² — eligible if you have at least one weight-related health condition (type 2 diabetes, prediabetes, hypertension, dyslipidaemia, obstructive sleep apnoea, or cardiovascular disease history)
For South Asian, Chinese, Black African, or Black Caribbean adults:
- BMI 27.5 kg/m² or above — may be eligible, as these groups face higher risk of type 2 diabetes and cardiovascular disease at lower BMI levels
To calculate your BMI, use our free BMI calculator above — simply enter your height and weight in kg or stone, and it will calculate your BMI instantly and show you where you fall within NHS categories.
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.
BMI Limitations and Individual Assessment
BMI is a useful screening tool but has important limitations. It cannot distinguish between muscle and fat, so athletes or very muscular individuals may have a high BMI despite low body fat percentage. BMI also doesn't account for where fat is stored — waist circumference matters too. The NHS recommends measuring waist circumference alongside BMI: increased risk for men over 94cm (37 inches), high risk over 102cm (40 inches); for women, increased risk over 80cm (31.5 inches), high risk over 88cm (34.5 inches). Your prescriber will consider your overall health picture, not just your BMI number, when assessing whether Mounjaro is 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.
Is BMI the only factor for Mounjaro eligibility?
No. While BMI is the main screening measure, prescribers also consider your weight-related health conditions, waist measurement, age, other medications, and medical history. Some conditions like gallbladder disease or pancreatitis history may affect eligibility. Your GP will assess your full health picture before prescribing.
What if my BMI is 28 — can I get Mounjaro?
At BMI 28, you may be eligible if you have a weight-related health condition such as type 2 diabetes, high blood pressure, or heart disease. If you don't have these conditions, the standard threshold is BMI 30. Only a prescriber can assess your individual eligibility after a clinical consultation.
Do the BMI thresholds differ by age?
The standard NHS BMI categories (18.5–24.9 healthy, 25–29.9 overweight, 30+ obese) apply to adults aged 18–65. For adults over 65, some prescribers may consider slightly higher thresholds, and children use different growth chart percentiles. Your prescriber will consider your age when making decisions.
How do I calculate if my weight meets the minimum BMI for Mounjaro?
Use the free BMI calculator on this page — enter your height (in cm or feet/inches) and weight (in kg or stone/lbs), and it will instantly show your BMI and which NHS category you fall into. This gives you a clear starting point before speaking to your GP.
What happens after I'm approved — does my BMI need to stay above the minimum?
Once Mounjaro treatment starts, the focus shifts to your health outcomes, not just maintaining a specific BMI. Your prescriber will monitor your progress, health improvements, and how you respond to the medication. The goal is sustainable health improvement, not hitting a target BMI.
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.