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That chart that proves that measuring weight by BMI is a load of BS.

Image via iStock.

There are many ways you can assess your health, but one of the most common has become the Body Mass Index (BMI) scale.

A tool primarily used to identify people who have adverse health risks such as heart disease, it’s used by doctors, nutritionists and fitness experts alike – but has continually come under fire for its flaws.

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And now one simple chart has highlighted its issues even further.

Image via bodylab.com

Created by Body Lab, each of these figures are the same height (175cm), weight (78) and BMI (25.5) - but you'd never have guessed.

The chart demonstrates how people with the same BMI (and 25.5 is in the healthy range) can have totally different body shapes - and thus different health risks.

So why is this?

"BMI is just a simple maths equation - (weight in kg/(height in metres squared))", explains clinical nutritionist Gabrielle Maston.

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"Your number falls into different categories that determine your health risk. The categories are:

Healthy 18-24.9
Over weight (low risk) 25-29.9
Obese (moderate risk) 30-34.9
Obese class 2 (high risk) 35- 39.9
Obese class 3 (extreme obesity) 40+ (Post continues after gallery.)

And as the chart demonstrates, it's flawed when it comes to different body shapes, which Maston argues means it should not be used in isolation to determine someone's health status.

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"There are major issues with people from different cultural heritages, for example Indian-Asian heritage tend to be smaller builds so the BMI will fall into the healthy range, but they carry an uneven distribution of fat around the waist, which is a good indicator of diabetes risk," she says.

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"People who are small but carry a significant amount of body fat and no muscle (otherwise known as 'skinny fat') are also a group for whom BMI is inaccurate," she explains.

Maston believes some of these problems are due to the studies the equation was derived from.

"They used university student-based populations as a test group, which means BMI is not completely accurate across cultural population groups," she explains. (Post continues after gallery.)

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It can also cause problems for people who are athletic and do a lot of weight-based exercise.

"If someone carries a lot of muscle mass and is quite athletic, again BMI is inaccurate," she says.

"It sometimes puts body builders or female weight lifters in the overweight category, because they weigh more, but this is not a true reflection of health status."

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"As we know, muscle weighs more than fat, so this needs to be taken into consideration. Muscle is healthy weight," she says.

However Maston believes we shouldn't scrap it completely.

"I think it's a good tool to use in a clinical setting with clients who do not participate in regular activity and already have signs of chronic illness," she says.

Maston argues BMI can be useful for people who don't exercise regularly. Image via iStock.

"It is not useful for children, teens and anyone that participates in weight-bearing sports like football or weight lifting."

"I do not use it in isolation. Combining BMI, waist circumference and a full blood test is a good comprehensive view of someone's general health," she says.

Do you think we should stop using the BMI scale?