Obesity in Childhood: definition and epidemiology

Obesity is defined as a condition where a pathological excess of body fat is present in an individual. Obesity develops when there is a discrepancy between energy intake and energy output. During its development the original steady-state is disturbed and after a period of positive energy balance, a new steady state at a higher level with an increase in body fat stores is achieved. Since the amount of body fat per se is difficult to determine exactly, for practical use, percentage overweight or the body mass index (BMI) is used to define and to track obesity in childhood. For a given BMI, adiposity varies with age, sex and ethnicity; however, BMI correlates reasonably well with body fat mass and the risk of obesity related diseases. Childhood obesity is one of the most complex and poorly understood clinical syndromes in pediatrics. Obesity is a common nutritional disorder among children and adolescents in the world. The percentage of overweight children and adolescents has increased by almost 50% in the past two decades. It has also been observed that about 40% of overweight children continue to have increased weight during adolescence and 75-80% of obese adolescents become obese adults. The majority of obesity in adulthood has its origin in childhood, which makes obesity a pediatric concern and the prevention and treatment of obesity a pediatric goal.