Perception of Body Image, Physical Activity and Sedentary Behavior among African-American, Mexican-American and Caucasian Adolescents

Thesis (Master's)--University of Washington, 2018Background: There is strong evidence that overweight and obesity rates among adolescents in the U.S. have increased over the last several decades. The aim of this study was to examine how perceived body image is related to how adolescents, aged 11-18, engage in physical activity and/or sedentary behavior, important in obesity prevention and adolescent health. Methods: This mixed-methods study used cross-sectional data collected between 2006-2008, on adolescents in Seattle, WA and Los Angeles, CA (N=486) as part of the Quality of Life of Overweight Youth: A Multicultural View study. Quantitative data was collected using a self-administered survey questionnaire. Qualitative data was collected using semi-structured interviews. Perceived body image was characterized using the Pictorial Body Image Assessment (score 1-13). Outcomes related to physical activity and sedentary behavior were collected using responses to questions about number of daily physical activity behavior in a week that cause an individual to sweat and breathe hard or not and number of hours of sedentary behavior in an average week, such as TV watching, video games or computer use. Unadjusted and adjusted linear regression models were used to test associations of perceived body image with physical activity and sedentary behavior. Potential confounders included race/ethnicity, age, gender, site, and mother’s educational attainment. Qualitative interview responses were reviewed to identify evidence of barriers and motivating factors for physical activity or sedentary behavior. Results: The mean age of participants was 14.8 years. Over 2/3 of participants were overweight or obese, with a mean body mass index (BMI) of 27.7 kg/m2 and mean perceived body image score of 4. On average, participants engaged in 3-4 days a week on any physical activity and 2-3 hours a day on TV watching, video game and computer use. Perceived body image score and standardized BMI were moderately correlated (r=0.66, p-value < 0.001). Perceived body image was inversely associated with physical activity of at least 20 minutes a day that caused an adolescent to sweat and breathe hard (β -0.121; 95% CI: -0.23, -0.02; p-value 0.024). Perceived body image was positively associated with TV watching for at least 30 minutes a day (β 0.093; 95%CI: 0.01, 0.18; p-value 0.034) after adjustment for confounders. The majority of adolescents felt they were only somewhat active in comparison to their peers, although many were aware of the importance of physical activity. They also mentioned family encouragement as a motivating factor for engaging in physical activity, and physical capability as a common barrier. Conclusion: Adolescent’s perceived body image is associated with physical activity and sedentary behavior. This may have implications in considering strategies to improve perceived body image accuracy, increase physical activity, and reduce sedentary behavior among adolescents of different sizes