What Is Obesity?

Obesity is defined as having a Body Mass Index (BMI) of 30 or higher.

(Overweight is defined as having a BMI between 25 and 29.9.)

BMI is calculated from a person’s weight and height and provides a reliable indicator of body fatness for most people. It is used to screen for weight categories that may lead to health problems.

Overweight and obese individuals are at increased risk for many diseases and health conditions, including the following:

  • Hypertension
  • Dyslipidemia (for example, high LDL cholesterol, low HDL cholesterol, or high levels of triglycerides)
  • Type 2 diabetes
  • Coronary heart disease
  • Stroke
  • Gallbladder disease
  • Osteoarthritis
  • Sleep apnea and respiratory problems
  • Some cancers (endometrial, breast, and colon)

What does your BMI mean?

BMI Weight Status
Below 18.5 Underweight
18.5 – 24.5 Healthy Weight
25.0 – 29.9 Overweight
30.0 and Above Obese

(For adults 20 years and older)

BMI For Adults Widget


(Use this calculator for adults, 20 years old and older)

BMI is calculated differently for children (2 years and older) and teens because it is age- and sex-specific and is often referred to as BMI-for-age. A child or teen’s BMI number is plotted on the CDC BMI-for-age growth charts to obtain a percentile ranking which assesses the relative position of the child’s BMI number among children of the same sex and age. BMI is a tool that helps identify possible weight problems for children and teens.

BMI-for-age weight status categories and the corresponding percentiles

Weight Status Category Percentile Range
Underweight Less than the 5th percentile
Healthy weight 5th percentile to less than the 85th percentile
Overweight 85th to less than the 95th percentile
Obese Equal to or greater than the 95th percentile

BMI Percentile Calculator for Children and Teens

View the Obesity Trends Among U.S. Adults Between 1985 and 2010

The data shown in these maps were collected through CDC’s Behavioral Risk Factor Surveillance System (BRFSS). Each year, state health departments use standard procedures to collect data through a series of telephone interviews with U.S. adults. Height and weight data are self-reported.


Summary of the data presented in the maps:

  • In 1990, among states participating in the Behavioral Risk Factor Surveillance System, 10 states had a prevalence of obesity less than 10% and no state had prevalence equal to or greater than 15%.
  • By 2000, no state had a prevalence of obesity less than 10%, 23 states had a prevalence between 20-24%, and no state had prevalence equal to or greater than 25%.
  • In 2010, no state had a prevalence of obesity less than 20%. Thirty-six states had a prevalence equal to or greater than 25%; 12 of these states (Alabama, Arkansas, Kentucky, Louisiana, Michigan, Mississippi, Missouri, Oklahoma, South Carolina, Tennessee, Texas, and West Virginia) had a prevalence equal to or greater than 30%.

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