The clinical definition of obesity is weight that is higher than what is considered a healthy weight for a given height, with a body mass index of 30.0 or more, states U.S. Centers for Disease Control and Prevention. An adult with a BMI of 30.0 meets the definition of obese.
For children and teenagers, BMI is age- and sex-specific because of the differences in body compositions between children of different sexes and ages, adds the CDC. Obese children measure at the 95th percentile or higher for children of the same sex and age.
For a healthy weight range, BMI measures 18.5 to 24.9 and 5th percentile to under the 85th percentile for adults and children, respectively, according to the CDC.