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
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
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
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