According to the body mass index (BMI) = weight (kg) ÷ the square of height (m):

Underweight: below 18.5;

Normal weight:18.5-24.9;

Overweight: 25-29.9;

Weight obesity: 30.0-34.9;

Severe obesity: 35.0-39.0.

If the body mass index is 20 (normal weight: 18.5-24.9) and the weight is 45 kg, it is 90 kg.

Extended data:

Body mass index, also known as body mass index, is calculated by dividing weight (kg) by the square of height (m) (calculation formula: body mass index = weight (kg)/ height (m)2). At present, the evaluation criteria in China are that the body mass index is less than 18.5, overweight when the body mass index is between 24 and 28, and obese when it is 28 or above.

Obviously, judging from the body mass index, this Zhihu netizen is also a thin man with low weight. In recent years, the detection of body composition has also entered the public's field of vision, gradually appearing in the physical examination items of hospitals and the evaluation of exercise effect in gymnasiums, and even ordinary people will prepare body fat scales to monitor daily body shape changes.

The ideal body mass index for adult males is 22, and that for adult females is 2 1.

Standard (ideal) weight = ideal BMI× height 2(m2). It is normal that the body weight accounts for 85% ~ 1 15% of the standard body weight. The ideal skeletal muscle mass of adult men is 47% of the standard weight, and that of adult women is 42%. The normal range of skeletal muscle content is 90% ~ 1650.

People's Health Network-Really Thin or Fake Thin? Don't be fooled by your weight.