Body mass index

Body Mass Index or BMI is a number calculated using height and weight, and sometimes gender or age (in children) that aims to measure whether someone's weight is within a healthy weight range, or if they are underweight, overweight or obese. BMI values are used to aid diagnosis of certain illnesses, for example the presence or severity of anorexia nervosa, and metabolic syndrome.

BMI ranges in adults
The United States CDC uses these ranges for adults. For children and adolescents, alternative ranges are used.

The CDC regards a Body Mass Index of 30 or higher in adults as obesity. One in 3 people in the United States have obesity.

Cost and availability
BMI is extremely easy to measure and calculate, and can be assessed by patients at home.