BMI Requirements
BMI Calculator
Use our BMI calculator to check your eligibility for prescription weight loss treatments available in the UK.
Your Weight Loss Tools
Understanding BMI
A BMI under 18.5 indicates you may be underweight. This could mean you're not eating enough or may have an underlying health condition. Speak with your GP for advice.
A BMI between 18.5 and 24.9 is considered a healthy weight range. Maintaining this range through balanced nutrition and regular activity supports overall wellbeing.
A BMI between 25 and 29.9 indicates you may be overweight. Small lifestyle changes like healthier eating and increased activity can help you reach a healthier weight.
A BMI between 30 and 34.9 indicates obesity class I. This increases your risk of serious health conditions. Your GP can provide support and treatment options.
A BMI between 35 and 39.9 indicates obesity class II. This significantly increases health risks. Medical support and treatment options are available through your GP.
A BMI of 40 or above indicates obesity class III. This carries the highest health risks. Speak with your GP about treatment options including medication and specialist support.
Quick answers
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ody Mass Index (BMI) is a simple measurement that estimates whether your weight is healthy for your height. It is calculated by dividing your weight in kilograms by your height in metres squared. BMI is commonly used as a screening tool to identify potential weight-related health risks in adults.
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For most adults, a BMI between 18.5 and 24.9 is considered within the healthy range. A BMI below 18.5 may indicate underweight, while a BMI between 25 and 29.9 is classed as overweight. A BMI of 30 or above is generally considered obese. These ranges are guidelines and may not apply equally to everyone.
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BMI is a useful general indicator, but it does not directly measure body fat or overall health. Factors such as muscle mass, age, ethnicity, and body composition can affect results. For example, athletes may have a higher BMI due to increased muscle rather than excess body fat.
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Checking your BMI can help you understand whether your weight may increase the risk of health conditions such as heart disease, type 2 diabetes, and high blood pressure. It can also be a useful starting point for discussing your health goals with a healthcare professional.
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Yes — BMI is a key factor in determining eligibility for prescription weight loss treatments in the UK. Most treatments require a BMI of 30 or above, or a BMI of 27 or above with a weight-related health condition such as type 2 diabetes or high blood pressure. Eligibility criteria vary by treatment and prescriber, so an online consultation with a GPhC-registered pharmacy is the best way to confirm your options.
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The NHS uses the same BMI ranges for adult women and men: a BMI of 18.5–24.9 is considered healthy, 25–29.9 is overweight, and 30 or above is obese. However, BMI can be less accurate for women with high muscle mass or during pregnancy. Some clinicians also consider waist circumference alongside BMI for a fuller picture of health risk.
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Most prescription weight loss injections in the UK require a BMI of 30 or above, or a BMI of 27 or above if you have at least one weight-related condition such as high blood pressure, high cholesterol, or type 2 diabetes. Individual pharmacies and prescribers may apply additional clinical criteria during your consultation.
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BMI can be reduced through a sustained calorie deficit achieved via a balanced diet and regular physical activity. For those who struggle with lifestyle changes alone, prescription weight loss treatments may support meaningful and sustained weight reduction. MedEazy compares prices across GPhC-registered pharmacies so you can explore your treatment options safely and affordably.