Why is the height squared in BMI?

Body mass index (BMI) is a measure of body fat based on height and weight. It is calculated by dividing a person's weight in kilograms by the square of their height in meters. The reason why height is squared in the BMI formula is because it takes into account the fact that taller people tend to have more muscle mass than shorter people, and muscle weighs more than fat. This means that taller people can weigh more without being overweight or obese. By squaring height in the BMI formula, it gives more weight to height in the calculation, which helps to ensure that BMI is a more accurate measure of body fat for people of all heights.

For example, a person who is 6 feet tall (1.83 meters) and weighs 180 pounds (81.6 kilograms) has a BMI of 23.9. This is considered to be a normal weight for this person. However, if this person were only 5 feet tall (1.52 meters), their BMI would be 31.1, which is considered to be obese. This is because the shorter person has less muscle mass than the taller person, so their weight is more likely to be due to fat.

Squaring height in the BMI formula also helps to make BMI a more consistent measure of body fat for people of different body shapes. For example, a person who is very muscular may have a high BMI even if they are not overweight or obese. This is because muscle weighs more than fat. By squaring height in the BMI formula, it helps to level the playing field for people with different body shapes and ensures that BMI is a more accurate measure of body fat for everyone.