How to Calculate BMI and Understand Its Role in Weight-Management Treatment

If you have been researching weight-loss treatments such as Mounjaro or Wegovy, you have probably come across the term BMI. It is often one of the first things people check when exploring whether they may be suitable for treatment.

But what does BMI mean, how do you calculate it, and does your result decide whether you can get weight-loss medication in the UK?

Let's break it down in simple terms.

What Is BMI?

BMI stands for Body Mass Index. It uses your height and weight to estimate whether your weight falls within a particular range.

Healthcare professionals use BMI as one part of a wider health assessment. It can help identify possible weight-related health risks, but it does not tell the whole story. For example, BMI cannot distinguish between muscle and body fat.

How to Calculate BMI

Calculating your BMI is straightforward. You only need your weight in kilograms and your height in metres.

For example, if you weigh 80kg and are 1.70 metres tall, your BMI would be:

You can also use the NHS BMI calculator to check your result.

For most adults, the usual BMI categories are:

These ranges may need adjusting for some ethnic backgrounds because health risks can occur at lower BMI levels. BMI is a screening tool, not a diagnosis.

What Is the BMI for Mounjaro Eligibility in the UK?

The BMI for Mounjaro eligibility depends on whether you are exploring private treatment or NHS access.

For weight management, the licensed criteria generally include adults with a BMI of 30 or above, or a BMI of at least 27 with a weight-related health condition. A prescriber must also assess whether the medicine is suitable for you.

NHS access has additional restrictions and is being introduced in phases. For example, NHS England's initial primary-care criteria require a BMI of at least 40, adjusted for certain ethnic backgrounds, alongside four specified weight-related health conditions.

What Is the BMI for Wegovy Eligibility in the UK?

The BMI for Wegovy eligibility for weight management is generally similar under its licensed indication: a BMI of 30 or above, or 27 or above with at least one weight-related health condition.

However, meeting these numbers does not guarantee a prescription. Your medical history, current medicines and overall health will also be considered. NHS eligibility may be narrower than private prescribing criteria.

Why Should You Track Your BMI Over Time?

Your BMI can provide a useful starting point, but it is not the only measure of progress. Waist measurements, symptoms, activity and changes over time can give you a broader picture.

If you are managing a prescribed GLP-1 treatment, the GLP-1 Offers App can help you stay organised with weight and BMI tracking, progress trends, symptom tracking, injection reminders and GLP-1 price alerts.