Longitudinal changes in overweight and obesity in Mexican American adolescents: The role of sociodemographic and behavioral characteristics

Mexican American (MA) youth have disproportionately experienced the escalating obesity epidemic. Research is needed to understand the factors that contribute to and protect against excess weight gain in this population. We examine changes over time in the prevalence of overweight and obesity (using age and gender-specific CDC cut-offs of 85th and 95th percentiles, respectively) in 1,154 MA adolescents, who were on average 12 years of age at baseline. We then identify sociodemographic and behavioral factors associated with changes in overweight and obesity. From 2005 to 2008, average body mass index (BMI) based on measured height and weight increased from 23 to 25. Obesity prevalence was approximately 33% at baseline and follow-up, with boys significantly more likely to be obese than girls (p<0.001). Over time, 11% of normal weight and overweight, non-obese adolescents became overweight and obese, respectively, whereas 12% of adolescents who were overweight or obese at baseline shifted to a lower BMI percentile. Bivariate analyses indicated that the probability of becoming overweight/obese was associated with female gender, younger age, U.S. parental nativity, and longer parental residence in the U.S. The probability of lowering one's weight was associated with greater physical activity reported at follow-up and greater parental education. Parent and adolescent acculturation, adolescent nativity, smoking and TV viewing reported at follow-up were not associated with changes in weight. Different factors contributed to the probability of becoming overweight compared to reducing weight over time and should be considered for strategies to reduce the obesity epidemic in MA adolescents. Pubertal status and body composition were not measured; thus weight percentile might reflect body fat or muscle.