What BMI Means for Weight-Loss Injections
How BMI is used to assess eligibility for weight-loss medications like Mounjaro and Wegovy, and its limitations.
Try the BMI Calculator for Mounjaro
BMI and medication eligibility
In the UK, weight-loss medications like Mounjaro and Wegovy are generally prescribed for adults with:
- A BMI of 30 or above (obese), or
- A BMI of 27 or above (overweight) with at least one weight-related health condition
BMI is calculated as weight (kg) divided by height (m) squared. It is a screening tool, not a definitive health measure.
BMI categories
| BMI | Category |
|---|---|
| Under 18.5 | Underweight |
| 18.5–24.9 | Healthy weight |
| 25–29.9 | Overweight |
| 30–34.9 | Obese class I |
| 35–39.9 | Obese class II |
| 40+ | Obese class III |
Limitations of BMI
- Does not distinguish between muscle and fat
- May underestimate risk in some ethnic groups (NICE recommends lower thresholds for South Asian populations)
- Does not account for body fat distribution (waist circumference is also important)
- Should not be used as the sole criteria for treatment decisions
Try the calculator
Use our BMI Calculator for Mounjaro to find your BMI and see weight benchmarks for your height.
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Related calculators
- BMI Calculator for Mounjaro — Find your BMI, see which category it falls into, and understand how it relates to eligibility criteria for treatments like Mounjaro.
- Mounjaro Weight Loss Calculator — This planning tool projects how much weight you could lose over a chosen number of weeks, using conservative, moderate, or ambitious assumpt
- Mounjaro Protein Calculator — Find out how much protein you should aim for each day and per meal to support muscle preservation during weight loss on GLP-1 medication.
- Mounjaro Calorie Calculator — Calculate your maintenance calories and a safe deficit range to support steady weight loss alongside Mounjaro treatment.
- Mounjaro Calorie Deficit Calculator — Enter your maintenance calories and a target intake (or desired weekly loss) to see the size of your deficit and projected weight change ove
- Mounjaro vs Wegovy Calculator — Enter your weight and the monthly costs of each medication to compare projected weight loss, total spend, and cost per kilogram lost over yo
Related guides
- How Many Calories Should You Eat on Mounjaro? — Understanding your calorie needs during Mounjaro treatment — maintenance, deficit, and safe intake ranges explained.
- How Much Protein Should You Eat on Mounjaro? — Why protein matters during GLP-1 weight loss and how to hit your daily target with practical meal guidance.
- How Much Weight Can You Lose on Mounjaro? — A realistic look at expected weight loss on Mounjaro (tirzepatide), based on clinical trial data and practical planning advice.
- Mounjaro vs Wegovy for Weight Loss — A balanced comparison of Mounjaro (tirzepatide) and Wegovy (semaglutide) — mechanism, effectiveness, cost, and side effects.
Last updated
Last reviewed: 2026-04-12T10:29:26.079Z.