Editors' ChoiceObesity

Growing Bigger in Kindergarten

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Science Translational Medicine  26 Feb 2014:
Vol. 6, Issue 225, pp. 225ec38
DOI: 10.1126/scitranslmed.3008711

Although the prevalence of childhood obesity in the United States, as well as in other Western countries, has plateaued during the past decade, the rates of obesity between the ages 6 and 11 years are still nearly 4 times as high as they were in 1965. Surprisingly, there is limited information on the incidence of childhood obesity, even though it is a major health problem.

A recent study by Cunningham and coauthors evaluated the incidence of obesity among 7738 children who were in kindergarten in 1998 in the United States. The kids were followed until the age of 14 years with repeated measurements of body weight and height. As children entered kindergarten, as many as 12.4% were already obese, with another 14.9% being overweight. The highest annual incidence of obesity, with additional 5.4% of children progressing to obesity, was recorded during kindergarten. The incidence rates decreased significantly between fifth and eighth grade to less than 2% per year. Of interest, most kids who were diagnosed with obesity between the ages of 5 and 14 years were already overweight or had high-normal body weight during kindergarten. The study also identifies additional risk factors for increased incidence of childhood obesity, with significantly higher rates observed among children who had high birth weight (≥4000 g, or ≥8.8 pounds). Higher incidence rates were also recorded among non-Hispanic blacks and among children in the middle quintile for socioeconomic status. Children from the highest socioeconomic status and non-Hispanic whites had the lowest rates of overweight and obesity.

Although the study does not report the incidence of obesity before the age of 5 and after the age of 14 years, it provides insights into the nature of the obesity epidemic among children. It appears that the critically vulnerable age for the development of overweight and obesity is around the age of 5 years or even earlier. These findings highlight the importance of further research to understand the factors associated with the early and rapid development of overweight during the first years of life. The authors speculate that obesity-prevention efforts should be focused on overweight kindergarteners, who are most susceptible to becoming obese during later childhood and adolescence.

S. A. Cunningham et al., Incidence of childhood obesity in the United States. N. Engl. J. Med. 370, 403–411 (2014). [PubMed]

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