What Is Body Mass Index?

what is Body Mass Index

What is Body Mass Index?

BMI is a measure of weight proportionate to height. Generally, BMI is considered an effective way to evaluate whether a person is overweight or obese, though there are exceptions to the rule. Some muscular people may have a BMI that puts them in the overweight range. However, these people are not considered overweight because muscle tissue weighs more than fat tissue.

According to the National Heart, Lung, and Blood Institute (NHLBI), a BMI from 18.5 to 24.9 is considered normal while a BMI of more than 25 is considered overweight. A person is considered obese if the BMI is above 30, and morbidly obese if the BMI is above 40.

BMI Ranges

  • Underweight = 18.5 or less
  • Normal weight = 18.5-24.9
  • Overweight = 25-29.9
  • Obesity = 30 or greater


What is Body Mass Index