What is a healthy BMI?

What is a healthy BMI?

Body mass index (BMI) is a measure for indicating nutritional status in adults.
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It is calculated by dividing a person’s weight in kilograms by the square of their height in metres (kg/m2).

The World Health Organisation gives the following example: “An adult who weighs 70 kg and whose height is 1.75 m will have a BMI of 22.9”.

70 (kg)/1.752 (m2) = 22.9 BMI

According to the World Health Organisation, for adults over 20 years old, BMI falls into one of the following categories.

What is a healthy BMI?


Nutritional status

Below 18.5



Normal weight




Obesity class I


Obesity class II

Above 40

Obesity class III

BMI in children and teens

BMI calculations differ when it comes to children and teens and should not always be used as a tool.

According to the American cancer society, this is “because the normal amount of body fat changes with age in children and teens, and is different between boys and girls”.

Why having a healthy BMI matters for your overall health

Having a healthy BMI isn’t just about looking healthy, it also has an impact on a range of other health conditions, such as:

  • High blood pressure
  • High cholesterol
  • Body pain
  • Stroke
  • Heart disease
  • Type 2 diabetes
  • Early death

What are the limitations of BMI?

BMI is limited in the sense that it doesn’t always give a valuable insight into the true health of the person. For example, it does not take into account whether your weight is predominantly fat or muscle. This can often be the case for weight lifters or professional athletes.

How to maintain a healthy BMI

Did you know? Losing as little as 5% of bodyweight can have a positive impact on heart health. Read Cigna's tips for achieving a healthy BMI.

Eating your 5 a day of fruit and vegetables will help you take in plenty of good protein and fibre. You can also improve your diet by limiting your salt and sugar intake.

Try watching the portion size of the meals that you are having. Opting for a smaller portion every now and again will be a big help in the long run.

When it comes to exercise, we recommend that you aim for at least 2.5 hours of cardio per week. This can include, jogging, a brisk walk or playing sports.

Maintaining a healthy BMI is a key step and remember that is important to stay healthy overall, especially for those who are constantly on the go with a busy lifestyle.

A helpful tip here would be to create a solid food plan, to help you plan ahead and stay ahead of the game. Remember that it is important not only to create a plan, but to stick to it. Your doctor can advise you on how many calories you should be consuming to lose/gain/maintain your weight.

Drinking at least 2.5 litres of water a day will also be very helpful for your BMI.

Another top tip would be to do muscle training at least twice a week. If you are a member of a gym, be sure to dedicate specific sessions to muscle building.

Continue reading:

Now that you know about BMI and how to maintain a healthy one, find out where the healthiest countries are around the world.

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