BMI or Body Mass Index refers to the proportion of your weight with respect to your height. This is a measure used to get the body composition of a person. A person with a 24 BMI is considered to be normal/healthy. This just means that this person has a lower chance of getting any health related diseases. BMIs that range under 18.5 are considered underweight; while a BMI between the range of 25 to 29.9 is overweight; and people who are obese have a BMI that ranges from 30 or higher.