The Incidence of Overweight and Obesity in Southern Adolescents

Year: 2003

Research Center: Southern Rural Development Center, Mississippi State University

Investigator: Warner, Mellie L.

Institution: Clemson University

Project Contact:
Mellie L. Warner
Clemson University
Phone: 864-654-5080


Obesity has emerged as a critical health issue in the United States, particularly among children and adolescents. Previous research has noted that the percentage of overweight children has accelerated significantly among African Americans and Hispanics from 1986 to 1998, with over 20 percent of these children now classified as overweight. Furthermore, the largest proportion of overweight children has been found in the U.S. South. To explore overweight and obesity among adolescents in the South, this study used data from the National Longitudinal Survey of Adolescent Health (Add Health).

The Add Health data were collected in two waves between 1994 and 1996 to explore health-related behaviors of adolescents enrolled in grades 7 through 12. Data at the individual, family, school, and community levels were collected from a school-based cluster sample of over 20,000 students. The study focused on how the students' social context (such as families, friends, peers, schools, and communities) contributed to their health and risk behaviors.

In 2001 and 2002, Add Health respondents age 18-26 were re-interviewed in a third wave to investigate the influence that adolescence has on young adulthood. This study used the Wave I and III data to explore the relationships between a student's Body Mass Index (BMI) and other personal, family, school, and community characteristics. Age- and gender-specific BMI were calculated for individuals at Wave I and Wave III using a program developed by the Centers for Disease Control and Prevention (CDC), so each student was classified as very underweight, underweight, normal weight, overweight, or obese. The study focused on 7,600 students enrolled in schools in the Southern region of the United States. Whenever appropriate, the Southern cohort was compared with students from other regions of the United States.

Multiple linear regression and logit models delineated the most important factors contributing to the BMI percentile of students at Wave I. BMI percentiles were significantly higher among males, African Americans, and Hispanics (when compared with non-Hispanics). Students who rarely socialized tended to be heavier, and the number of hours spent in sedentary pursuits had a small, but significant, impact on their BMI percentile. Student exercise had a positive relationship with BMI, suggesting that exercise may have contributed to more muscle development.

Family factors were important in explaining students' BMIs, particularly parental obesity. Household income had a negative impact on BMI, suggesting that students from more affluent households were less likely to be overweight or obese. BMI percentiles tended to be lower among students who were breastfed for 3 months or longer, who judged their health to be excellent or very good, who ate breakfast on a regular basis, who suffered no disabilities, and who had reached their physical (sexual) maturity.

Comparison of participants' BMIs at Wave III and Wave I showed that weight gains were far greater among Southerners than those living in others regions of the country. Fifty-three percent of African American females in the South were either obese or overweight at Wave III, versus 39 percent for African American females located in other regions of the United States. Multiple regression exploring changes between Wave I and Wave III participants' BMIs indicated that many of the factors that proved important in Wave I analysis remained significant at Wave III. Wave III included items to capture activities and habits of participants during their early adulthood. Persons who spent more hours playing sports in a week, or who walked to school or work, were less likely to be overweight or obese. Dieting and exercising to lose weight at Wave I was linked to larger weight gains in Wave III. Obesity tends to be multi-generational with obese parents, especially the mother, having overweight or obese adolescents. Moreover, these adolescents gained more weight than their peers as they moved into young adulthood.

These study findings suggest several program implications. Given the multigenerational nature of obesity indicated in this study, programs to prevent or reduce obesity should focus on the entire family. Wave I findings indicated that lack of knowledge by parents was a key factor among overweight/obese children, indicating a role for nutrition education. An emphasis on healthy food (including breakfast) and an active lifestyle may prevent weight gain among young people. In young adulthood, team and individual sports have a larger impact on moderating weight gain than other exercise, though both tend to reduce weight gain. Walking to work or school has a negative impact (4-6 pounds less gained) on weight gain and should be encouraged. Communities could help by including safe walking routes in their development plans.