The body mass of an individual indicates whether they are maintaining a healthy weight and a useful tool in identifying whether the patient may be at risk for other medical conditions. The Body Mass Index uses weight and height in calculating a number that classifies the person as: underweight, at ideal weight, overweight or obese, according to the Centers for Disease Control and Prevention.
A BMI below 18.5 indicates the patient is underweight; persons with a BMI ranging from 18.5 to 24.9 are considered to be of ideal weight. Those with a BMI ranging from 25.0 to 29.9 are classified as overweight, while a body mass index 30.0 or greater indicates obesity, explains the Centers for Disease Control and Prevention.
The same standard weight categories are used to interpret the body mass index of adult women and men of all ages. However, since girls and boys mature at different rates, BMI is evaluated differently in children and teens.
As of 2015, an estimated 1.5 billion adults over the age of 20 -roughly 34 percent of the adult world population- are overweight or obese, according to data supplied by the Harvard School of Public Health.
For research and clinical purposes, obesity is divided into three categories; Class I and Class II obesity range from 30.0 to 34.9 and 35.0 to 39.9, respectively. Persons suffering from Class III obesity have a BMI of 40.0 or greater.