0 to 29.9; Class I obesity, 30.0 to 34.9; Class II obesity, 35.0 to 39.9; and Class III obesity, 40.0+. The WHO (2000) terminology differs slightly, but the cutoff points are the same. As explained by Gere (1998, p. 20) "In growing children, in whom weight and height are both changing (and at different rates), the definition of obesity is inherently more complicated". Although no universally agreed on standard exists for assessing overweight and obesity in children and adolescents, there is a growing consensus that BMI should be adopted as an indirect measure of adiposity for children and adolescents, as well (Barlow & Dietz, 1998). .
Because BMI varies substantially by age and gender during childhood and adolescence, the specific BMI cutoffs used to classify obesity must be gender- and age-specific and must be referenced against a standard. In the United States, the standard used is the CDC Revised Growth Reference (Barlow & Dietz, 1998). Internationally, several standards (Cole et.al, 1995; Ogden et al., 2002), including one based on a pooled international sample (Cole et.al, 2000), are also in use.
Several periods in development have been proposed as critical periods in the development of persistent obesity and its comorbid consequences. These include the prenatal period (when intrauterine exposures may influence adiposity), early childhood, and adolescence. Some evidence suggests that breast-feeding may protect against later obesity. Likelihood of persistence in adulthood of obesity from childhood is related both to age at onset and severity.
Sequelae.
Childhood obesity has a number of immediate, intermediate, and long-term health consequences (Must & Strauss, 1999). These include classic cardiovascular risk factors, such as high blood pressure, abnormal blood lipid levels, and impaired glucose tolerance. Respiratory conditions include sleep-disordered breathing. In addition, early menarche and menstrual abnormalities are linked to overweight.