The BMI in the medical report refers to the Body Mass Index.

Body Mass Index (BMI, Body Mass Index) is an important standard used internationally to measure the degree of obesity and the health of the human body, mainly for statistical analysis. The degree of obesity can not be judged using the absolute value of weight, which is naturally related to height. Therefore, BMI is a relatively objective parameter obtained through the two values of body weight and height, and the range of this parameter is used to measure the quality of the body.

BMI is a common measure of fatness and thinness, calculated by dividing weight (kilograms) by the square of height (meters). It is generally considered normal between 20 and 25, with more than 25 being overweight and more than 30 being obese.

Expanded:

According to Singapore's United Morning Post, which reported on November 5, the study found that that a body mass index (BMI) that is too high or too low is associated with an increased risk of death from a variety of disease factors. People with a BMI between 21 and 25 had the lowest risk of dying from cancer and heart disease.

With a BMI of 30 or higher, people have an increased risk of dying from cancer, heart disease, respiratory disease, kidney disease and diabetes. In general, life expectancy is reduced by 4.2 years for men and 3.5 years for women. But a low BMI is not good either, and again is associated with an increased risk of death from a wide range of diseases, including cardiovascular disease, respiratory disease and dementia.

Baidu Encyclopedia - BMI

People's Daily Online - Higher BMI numbers are not better! Too high or too low increases the risk of disease and death