Child And Adolescent Obesity Epidemiology And Developmental Perspectives

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Physiology & Behavior 94 (2008) 8 – 16 www.elsevier.com/locate/phb

Child and adolescent obesity: Epidemiology and developmental perspectives
Linda S. Adair ⁎
Department of Nutrition, Schools of Public Health and Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA Received 11 June 2007; accepted 15 November 2007Abstract From infancy through adolescence, more and more children are becoming overweight. National prevalence data show that more than 17% of youth have a body mass index (BMI) above the 95th percentile of the US age and sex-specific reference. Particularly alarming are rates in children as young as 2 years of age, and among minority children. Periods of heightened vulnerability to weight gain havebeen identified, and research supports the notion that obesity has its origins in early life. This paper focuses on susceptibility to increased adiposity during the prenatal period, infancy, mid-childhood and adolescence, and how factors operating in each of these periods influence risk of becoming overweight. Prenatal exposure to over or undernutrition, rapid growth in early infancy, an earlyadiposity rebound in childhood, and early pubertal development have all been implicated in the development of obesity. The persistence of obesity from young ages emphasizes the importance of understanding growth trajectories, and of developing prevention strategies to overcome strong influences of obesigenic environments at young ages. © 2007 Elsevier Inc. All rights reserved.
Keywords: Obesity;Infancy; Rapid weight gain; Adiposity rebound; Pubertal development; Adolescents

As noted in a vast literature published over the past decade, overweight and obesity in children and adolescents are a growing cause of concern globally because of alarming trends in prevalence, severity, and occurrence of adverse health and psychosocial consequences among youth. This paper offers an overview of thetrends in prevalence, followed by a developmental perspective on child and adolescent overweight and obesity that considers the nature of biological susceptibility at different ages from the prenatal period through adolescence. 1. Prevalence In the United States, the National Health and Examination Surveys (NHANES) document steady increases from the late 1970s to 2004 in the prevalence ofoverweight (having a body mass index – BMI – above the age and sex-specific 95th percentile of the US growth reference) and at risk of overweight (a BMI between the 85th and 95th percentile) among children and adolescents, ages 2 to 18 years. The percentage of overweight
⁎ Tel.: +1 919 966 4449; fax: +1 919 966 9159. E-mail address: ladair@email.unc.edu. 0031-9384/$ - see front matter © 2007 Elsevier Inc.All rights reserved. doi:10.1016/j.physbeh.2007.11.016

youth increased sharply from 1999 to 2004, so that by 2004, 17.1% of American children and adolescents were overweight, and an additional 16.5% were at risk of overweight. Nearly 14% of 2–5-year old children and 19% of 6–11-year old children were overweight [1]. In addition to increasing BMI, there have also been trends toward higher waistcircumference indicative of abdominal obesity, which is of concern because of its association with increased risk of type 2 diabetes and cardiovascular diseases. Li et al. [2] reported a 65% increase in waist circumference among boys and a 69% increase among girls from the 1988–94 to 1999– 2004 NHANES surveys. Marked race/ethnic differences can be seen in weight status trends, as shown in Fig. 1,drawn from the data presented by Ogden et al. [1]. The highest overall overweight prevalence was observed in African American and Mexican American youth. Comparing time trends within race/ethnic groups, African American 6- to 17-year old youth had much larger increases in mean BMI and overweight prevalence over the last 30 years compared to white children. In contrast, despite a higher overall...