Access Type

Open Access Dissertation

Date of Award

January 2012

Degree Type


Degree Name




First Advisor

Douglas Barnett


Adolescence represents a unique period of development that is filled with both opportunities and challenges. Choices and health patterns, such as sedentary activity or poor dietary intake, which are established during adolescence can set the stage for adulthood. Obesity in youth has emerged as a major health problem in the United States and across the globe (American Academy of Child and Adolescent Psychiatry, 2012). One way to help prevent obesity is by incorporating preventive intervention services into primary care health systems. The current study, therefore, evaluated the effects of a brief 1-session intervention delivered in a primary care setting in an attempt to promote healthy changes in diet and physical activity. The sample included 100 adolescents from the Children's Hospital of Michigan's Adolescent Medicine Clinic who were randomly assigned to one of two conditions: a) the full intervention called Motivating Adolescents To Chat for Health (MATCH) with a health coach, or b) the goal-only session. Health behaviors and individual characteristics (e.g., autonomous motivation, self-efficacy) were assessed at baseline and health behaviors were re-assessed at follow-up 1 month later. There was a 47% attrition rate. Those in the intervention group were more likely to participate in the follow-up portion of the study. Similarly, those with higher baseline motivation and self-efficacy were more likely to continue in the study. Results showed that those in the full intervention group did not show improvements above and beyond those in the goal-only condition. However, both groups did show health behavior improvements over time and older adolescents showed more improvements. There were complex relationships that predicted behavior change. At high levels of self-efficacy, there was a strong relationship between motivation and behavior change. Parental autonomy support appeared to have either no affect or a negative affect on behavior change. When parental autonomy support was low, motivation, self-efficacy, and behavioral intentions each appeared to relate more strongly to behavior change than when support was high. Parent-child relationship quality predicted positive changes in diet; however, for boys, a stronger parent-child relationship was related to lower physical activity at follow-up. When adolescents reported high problem recognition, there was a positive relationship between behavioral intentions and physical activity at follow-up. For adolescents with higher BMI's, greater behavioral intentions were related to greater changes in physical activity. The study demonstrates an important first step in integrating preventive care strategies into the primary care setting by focusing on the individual's values, goals, and intrinsic motivations.