Obesity and overweight is usually measured in the body mass index (BMI). A person's weight (in kilograms) divided by the square of his/her height (in meters).
A BMI of 18.5-24.9 suggests a normal healthy weight. If a persons BMI is over 25 it is considered overweight, and over 30 is generally considered obese. The method of measuring obesity with the body mass index can be misleading, because muscle mass weights more than fat. Therefore are young men who build muscle often in the zone of "overweight" without being overweight.