Body Mass Index (BMI)

Definition

A person with a higher weight than what is considered normal for a given height is categorized as overweight or obese.

BMI is calculated as weight (in kilograms) divided by height (in meters) squared. It is proportionate to the amount of fat in one's body and is used to determine overweight and obesity in adults (20+ years old) and children (<20 years old).

This online tool from the Centers for Disease Control and Prevention (CDC) can quickly calculate BMI for adults. This online widget can calculate BMI for children (ages 2 to 20).

Classification

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) defines overweight and obesity.

• Normal: 18.5 to 25

• Overweight: 25 to 30

• Obesity: 30 to 40

• Severe Obesity: above 40

Statistics

The National Health and Nutrition Examination Survey (NHANES), conducted from 2017 to 2018, provides data across the US.

Adults

• 30.7% are overweight.

• 42.4%have obesity.

• 9.2% have severe obesity.

Children

• 16.1% are overweight.

• 19.3% have obesity.

• 6.1% have severe obesity.