What is a body mass index (calculator included) and why you can’t believe it

People use certain metrics to measure their health. But what if the most common of them cannot be trusted? The Challenger decided to figure out what the body mass index is and why it is bad.

Body Mass Index (BMI) is an indicator that is calculated taking into account the height and weight of a person and gives a conclusion about what it is mass: insufficient, normal or excessive.

BMI is calculated by the formula I = m / h ², where m - body weight in kilograms, h - growth in meters. Measured in kg / m².

BMI calculator

Enter your weight in kilograms

Enter your height in centimeters

Calculate BMI

* it is proposed to enter the growth in centimeters - for simplicity, counting

In accordance with the calculated BMI indicator, any person can be attributed to one of the categories:

  • BMI 16-18 - mass deficit,
  • 18-25 - normal,
  • 25-30 - overweight,
  • 30-35 - obesity I degree,
  • 35-40 - obesity II degree,
  • above 40 - morbid obesity.

BMI was invented by a Belgian sociologist, statistician, mathematician, astronomer Adolf Quetelet in 1869-for statistics. He was going to derive the concept of "norm" (the average value on the scale of all possible options) for his theory of the "average person". Giving someone health advice based on BMI was not part of Quetelet's plans.

Nowadays, this indicator is widely used by doctors and fitness trainers.

I bet you at least once in your life calculated your body mass index?

What is a body mass index (calculator included) and why you can’t believe it

Photo: shutterstock. com

The idea of ​​measuring the degree of obesity a person taking into account the indications of his height and weight does not seem successful. And that's why.

Muscles are denser than fat and, therefore, weigh more. For this reason, it is illogical not to take into account the composition of the body, giving an estimate of the degree of obesity of a person.

A simple example: compare a stunted MMA fighter and a tall lover to lie on a sofa. With a height of 160 cm, a wrestler weighs 100 kg, and a guy who does not engage in sports weighs the same 100 kg, but with a height of 210 cm, the BMI of the wrestler in this case will be 39, which corresponds to obesity of the II degree, and the BMI of our lodger - 22 6, which is considered the norm. It is obvious that the muscle mass of the wrestler is much higher. In the course of the study, scientists found that a higher percentage of body fat increases the likelihood of death, and a higher percentage of muscle mass, on the contrary, reduces it.

Another example: BMI can grow in the same person if he begins to actively engage in sports - when fat is replaced by muscle mass, his weight can become more, and the figure becomes slimmer.

Therefore, give recommendations health, not considering body composition, is inappropriate.

There are three layers of fat in human body: superficial (subcutaneous fat), deep (between the muscles) and visceral (inside the abdominal cavity). And if subcutaneous fat is not harmful to health, then visceral can lead to serious


: diabetes, the development of cardiovascular disease, insulin resistance, and ultimately the increased risk of premature death.

Thus, the distribution of fat is the most important factor in determining health risks. But when calculating BMI, this is not taken into account.

In women and men have a different physique. Men have denser and heavier bones, more muscle mass. It is not possible to give health advice without taking this into account.

Р the distribution of fat changes with age. And these changes will be different for women and men.

The 20-year-old guy and his 75-year-old grandmother will have different body compositions, and this is normal.

What is a body mass index (calculator included) and why you can’t believe it

Photo: shutterstock. com

As we already said , BMI is calculated by two indicators: weight and squared growth. Such a relationship suggests that the taller the person, the fatter he is. But this does not at all reflect the real picture.

In addition, the female body can have many bends, which is also not taken into account in the calculations, and, for example, a girl with large breasts in terms of BMI will be less healthy than a girl with zero size.

BMI is a popular indicator for judging about shortage, norm or excess of a person’s body weight. But the formula does not take into account several important factors, such as body composition, fat distribution, gender, age, as well as body shape. Therefore, BMI is not always possible to judge the degree of obesity. For a more accurate determination of body composition, it is better to use bio-impedance analysis.



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