May 06, 2022 07:00:00

Why do experts point out that 'health is nonsense in BMI'?

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Body Mass Index (BMI) , which is calculated from the height and weight of a person, is widely used as an index showing the degree of obesity, and some people set a goal of 'aiming for a BMI of 23 or less' when dieting or remodeling. However, Dr. Nicholas Fuller , who studies obesity and cardiovascular disease at the University of Sydney's Department of Medicine and Health, and is the author of ' Interval Weight Loss for Life ,' said, 'Health with BMI. It is nonsense to talk about. '

Using BMI to measure your health is nonsense. Here's why
https://theconversation.com/using-bmi-to-measure-your-health-is-nonsense-heres-why-180412

In recent years, it has become common to 'manage people's health numerically', such as tracking daily steps and amount of exercise to create a fitness score, and scoring things such as heart rate and sleep quality. The market for smart watches is expanding. One of the most popular numbers for managing such health is 'BMI', which indicates the degree of obesity based on height and weight.

The concept of BMI was developed in 1832 by Belgian statistician Adolphe Quetelet . This index, which was called the 'Quetelet index' at that time, was developed for the purpose of explaining the 'average man' when the government estimates the obesity rate in the general population.

More than a century later, in 1972, American physiologist Ancel Keys conducted asurvey of more than 7,000 subjects, saying, 'The Quetelet index is among the best of the various indexes on obesity.' Insisted. After that, the Ketley index was renamed to 'BMI', and further research confirmed the association between BMI and diseases such as heart disease, liver disease, arthritis, cancer, diabetes, and sleep apnea syndrome, so BMI is a major index of health. Widely used as.

To calculate BMI, simply measure your weight in kg and divide your height by the square of your height in meters. For example, the BMI of a person with a weight of 70 kg and a height of 1.7 m is '70 ÷ (1.7 x 1.7) = 24.22 ...'.

BMI is classified into the following 4 categories according to the degree of obesity. The BMI of a person with a weight of 70 kg and a height of 1.7 m is about 24.22, so it falls under the category of 'normal' in the following categories.

・ BMI is less than 18.5 …… Low weight
・ BMI is between 18.5 and 24.9 …… Normal
・ BMI is between 25.0 and 29.9 …… Overweight
・ BMI is 30.0 or higher …… Obesity

Today, BMI is used in various places such as hospitals and gyms, but Fuller said, 'BMI is an accessible and inexpensive way to screen human health, but as a single measure of health. You shouldn't depend on it. ' The reason is explained as follows.

◆ 1: BMI does not consider body fat percentage
BMI is calculated based on height and weight, but the risk of getting sick in humans is more strongly related to 'body fat' than weight. Of course, the more body fat you have, the more weight you gain, so you can estimate your health condition to some extent even with BMI using weight, but BMI will not work well for people who have less body fat but more muscle. ..

To give an extreme example, the BMI of Usain Bolt (height 1.95m, weight 94kg), who holds the world record for the 100m dash, will be '24.72', and he will soon be 'overweight'. .. In addition, Tom Brady (height 1.93m, weight 102.1kg), who is famous as the best American football player in history, has a BMI of '27.41', which means that he is 'overweight' in terms of classification.

◆ 2: BMI does not measure body fat distribution
Past

studies have shown that not all body fats have the same risk, even for people with the same percentage of body fat, and that the risk of disease varies depending on 'where the body fat is stored'. increase. For example, a person with a large amount of visceral fat accumulated near the stomach is at higher risk of stroke, diabetes, heart disease, etc. than a person with a large amount of fat accumulated in the buttocks.

◆ 3: BMI does not consider racial or gender differences
Quetelet, who developed BMI, and Keith, who verified the accuracy of BMI, mainly targeted middle-aged Anglo-Saxon men, but the relationship between body composition and fat and disease varies depending on gender and race. It is generally known that women have less muscle mass and more fat than men, and that they lose muscle mass with age. It is also said that Asian people have a healthy BMI of 'less than 23', while Polynesian people have a BMI of 'less than 26'.

Fuller acknowledges that weight and health are certainly linked and that BMI can be used as a screening tool, but BMI alone is not enough to adequately assess health and disease risk. He pointed out that body fat and blood tests should be combined. 'BMI is a good indicator of your health, but it should never be the only measurement,' he said.