Body Mass Index (BMI)

Body Mass Index (BMI) is a tool that indicates if your weight is in a healthy range. By taking your weight and comparing it with your height, you can get a good indication of whether you’re in a healthy weight range
body mass index BMI calculator

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The Australian Government Department of Health lists five categories of weight ranges in BMI1:

  • Underweight - a BMI less than 18.5
  • Healthy - a BMI between 18.5 and 24.9
  • Overweight - a BMI between 25 and 29.9
  • Obese - a BMI greater than 30

How to you calculate your BMI

To check your BMI2, first, you need to measure your height and weight. Using a good quality, reliable scale, weigh yourself wearing as little clothing as possible. Then, measure your height using a tape measure.

The Australian Government Department of Health suggests using a tape measure attached to a straight wall, with the base at floor level. Then you should have someone else write down your height, by placing a flat ruler parallel to the top of your head 2.

The BMI formula

If you’d like to calculate your BMI the old fashioned way, the mathematical formula is:

Body Mass Index = weight (kg) ÷ height (㎡)

So, for example, let’s check the BMI of a person 1.7 metres tall and weighing 65 kilos.
We take their weight in kilos (65) and divide it by their height squared (1.7x1.7 =2.89) so we get:
65 ÷ 2.89 = 22.49

With a BMI of 22.49, this person is within the healthy weight range.

Does BMI change for men and women?

No, the formula for calculating BMI for men and women is the same. Gender plays no part in the calculations, neither does your age or ethnicity. For these reasons, your BMI doesn’t give a complete review of your current health.

What is a healthy BMI?

According to the Australian government, a healthy BMI is between 18.5 and 24.91. Typically, for any height, there is a 10-12 kilo safe range you can rank between and still be considered a healthy BMI.

For example, using our 1.7 metre tall person weighing 65 kilos, they can weigh between 53.5 and 72 kilos. So, there is a broad weight range you can fall into and still be considered a healthy weight. This allows for most genetic variations in body composition and type.

How can you improve your BMI?

If your BMI puts you in the overweight or obese category, there are several steps you can take to improve your lifestyle and create healthy habits. The Australian Government Department of Health suggests a program that includes:

  • Planning for success
  • Eating well
  • Getting active
  • Tailoring a program to your needs
  • Using free tools, like these meal and fitness planners

Shifting your habits to create a new lifestyle can be difficult, but there is plenty of help and support available3. With patience and perseverance, you can do it!

If you’re underweight and need to gain weight to improve your BMI, start by visiting the website which has plenty of resources for people needing to gain weight4.

If you have any questions or concerns about your weight, or your BMI, consult your doctor. Any lifestyle changes you decide to undertake based on your BMI should be done under medical supervision.

Waist measurement and your BMI

Another good way to determine whether you’re at a healthy weight is to measure your waist circumference.

The Australian Government Department of Health says that:

“Waist circumference is a better predictor than BMI of type 2 diabetes in women and of cardiovascular disease.1

So, it’s a good idea to consider your waist circumference as well as your BMI, in order to get a good picture of your overall health.

The Australian Government Department of Health also has some gender specific guidelines:4

  • For men: a waist circumference of 94 centimetres or more indicates an increased risk of chronic disease, and a measurement of 102 centimetres or more indicates a higher increased risk of chronic disease.
  • For women: a waist circumference of 80 centimetres or more indicates an increased risk of chronic disease, and a measurement of 88 centimetres or more indicates a higher increased risk of chronic disease.

If your waist circumference puts you at risk, it’s a good idea to talk to your doctor about a potential plan for improving your health.

Factors that may affect your BMI

While BMI is a very useful tool, it’s not a perfect, and is only part of determining the state of your overall health.

The Australian Government Department of Health says that the healthy BMI range can be:

  • Lower for people of Asian background
  • Higher for those of Polynesian origin
  • Higher for older people
  • Higher for elite athletes with higher than normal levels of lean body tissue

BMI is also not an accurate indicator of health in pregnant women or children1.

Want to compare health insurance?

Maintaining a healthy BMI is an important part of keeping your health in check. But unfortunately, unexpected events can occur in your life that may require medical treatment by a medical physician, and in a hospital. At iSelect, we can help you find a health insurance policy for your needs, comparing policies side by side from our range of providers.

Start comparing policies online today, or call us on 13 19 20.



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