Introduction to the special issue: pediatric overweight.

Over the past three decades, overweight has become a major health problem among children and adolescents. Using ageand gender-adjusted growth charts for children, overweight is defined as body mass index (BMI) (weight in kg/height in m) >95th percentile and at risk for overweight is defined as BMI >85th and <95th percentile (Centers for Disease Control and Prevention, 2006). There is no agreed-upon definition for obesity in children, although the term is often used. To avoid confusion, the articles in this Special Issue have tried to adhere to the formal definitions of overweight and at risk for overweight. Data from the most recent National Health and Nutrition Examination Survey (NHANES-IV) show that 17.1% of children and adolescents are overweight, an increase of 2.2% in females and 4.2% in males from 2002 to 2004 (Ogden et al., 2006). Not only is the epidemic of overweight increasing among children, but it begins early in life, with estimates of over 10% of preschoolers with a BMI above the 95th percentile, based on ageand gender-specific charts—double the expected rate. Recent studies have shown that rate of weight gain during the first few months of life can track into overweight during childhood (Dennison, Edmonds, Stratton, & Pruzek, 2006; Ong & Loos, 2006). Pediatric overweight is associated with both immediate and long-term health problems, including hypertension, asthma, musculoskeletal problems, obstructive sleep disorders, type II diabetes, depression, and social stigmatization (Cruz et al., 2005; Kiess et al., 2001). Not only do overweight children suffer physical and psychological risk (Reilly et al., 2003), but overweight status during childhood and adolescence is a significant risk factor for adult obesity and other chronic illnesses (Engeland, Bjorge, Tverdal, & Sogaard, 2004; Kvaavik, Tell, & Klepp, 2003; Whitaker, Wright, Pepe, Seidel, & Dietz, 1997). Although the development of overweight is a chronic disease that is influenced by genetic, metabolic, and physiological factors, there are environmental and psychological factors that contribute to overweight and therefore can be the focus of prevention and treatment efforts. The purpose of the Special Issue of the Journal of Pediatric Psychology on pediatric overweight is to focus on the environmental, familial, psychological, and health factors associated with pediatric overweight, with an ultimate goal of informing prevention and treatment.