The percentage of adolescents aged 15-17 who are overweight today is about 50 percent higher in families below the poverty line in comparison to those at or above it. That difference was not present in the 1970s and 1980s, according to researchers from the Johns Hopkins Bloomberg School of Public Health and other institutions. The scientists based their analyses on U.S. national health surveys spanning 33 years. Adolescents aged 15-17 who were in families with an income below the poverty line were more likely to have higher caloric intake from sweetened beverages, to be physically inactive and to skip breakfast. Each of these factors may have played a role in the growing difference in the percentage of overweight teens associated with family poverty. This trend was specific to adolescents aged 15-17 and was not found among adolescents aged 12-14. The study is published in the May 24/31, 2006, issue of the Journal of the American Medical Association (JAMA).

"The prevalence of overweight adolescents in the United States has more than doubled in the past three decades. And the percentage of adolescents who are overweight has increased significantly faster among the poor in comparison to the non-poor over the past decade," said Richard A. Miech, PhD, MPH, lead author of the study and an associate professor in the Johns Hopkins Bloomberg School of Public Health's Department of Mental Health.

The study authors analyzed four U.S. National Health and Nutrition Examination Surveys (NHANES)--1971-1974, 1976-1980, 1988-1994, 1999-2004. Children with a body mass index at or above the 95th percentile for their age and sex in the 2000 Centers for Disease Control and Prevention growth charts were classified as overweight. The authors found that 15- to 17-year-old adolescents with higher daily intake of calories from sweetened beverages were significantly more likely to be overweight. In addition, among high school adolescents, the percentage of daily calories from drinking sweetened beverages has increased by more than 20 percent over the past decade (from 10.7 percent to 13.2 percent). Sweetened beverage consumption also increased at a faster rate among poor versus non-poor adolescents (67 percent versus 14 percent). Today, high school adolescents who live below the poverty line are more likely to be physically inactive and also more likely to skip breakfast, both of which are associated with excessive weight gain. The researchers did not see this same trend in adolescents aged 12-14. However, non-poor black adolescents in this age range were more likely to be overweight than their poor counterparts.

The researchers note that as more and more adolescents gain excessive weight, the associated consequences--type 2 diabetes, hypertension, sleep apnea, poor quality of life and morbidity in adulthood--will also increase.

"I believe that the trend in poverty and adolescent obesity can be reversed, if there is sustained public will to do so. While there is no silver bullet that will end this trend or the obesity epidemic in general, we know many of the major factors involved and we are beginning to do something about them," said Miech. "The recent, voluntary withdrawal of soft drinks from schools is a good step. We need to further develop and implement additional programs to improve adolescent nutrition and physical exercise, especially among the poor."

Unlike definitions for adults, the Centers for Disease Control and Prevention uses "overweight" to refer to the highest body mass index for children and adolescents. Therefore, it is inaccurate to use the term "obese" when referring to elevated body mass index in this age group.

Study authors include Richard A. Miech, Shiriki K. Kumanyika, Nicolas Stettler, Bruce G. Link, Jo C. Phelan and Virginia W. Chang.

Kenna L. Lowe
paffairsjhsph.edu
Johns Hopkins University Bloomberg School of Public Health
jhsph.edu