Thanks for the links.
So, for adults, use the body mass index markers. Greater than 25 kg/m2 is considered overweight. Greater than 30 is considered obese. And, actually, there are three categories of obesity: obese I: BMI 30-34.9, obese II: BMI 35-59.9, and obese III (severe or morbid obesity): BMI greater than 40 (or 100 pounds or more overweight).
For children (generally age 2 to 18), use the CDC growth charts. Overweight in children is defined as a body mass index that is above the 95th percentile for his or her age on the growth chart. A body mass index that is above the 85th percentile means the child is
at risk of becoming overweight. The vast majority of children who are overweight are also obese.