Date of Award

1-1-2011

Document Type

Campus Access Dissertation

Department

Exercise Science

First Advisor

Steven N Blair

Abstract

This dissertation focuses on managing and understanding obesity. Three manuscripts were written addressing this topic. First, a meta-analysis was performed assessing the joint association between cardiorespiratory fitness and excessive body weight compared to mortality. After searching two databases and applying inclusion and exclusion criteria, 9 articles were included in the analysis. Individuals who are fat and also fit had the same risk of mortality (Hazard ratio and 95% confidence intervals, 1.12, 0.97-1.29) as normal weight and fit individuals. Furthermore, unfit individuals, regardless if they were normal weight (2.01, 1.63-2.48) or fat (2.09, 1.71-2.54), had twice the risk of death compared to normal weight and fit individuals. Second, the rationale, design, intervention and outcome measures of a randomized controlled trial were discussed. Third, data from the randomized controlled trial were analyzed to assess electronic (i.e. SenseWear Armband) lifestyle self-monitoring (i.e. physical activity and dietary intake) and its relation to weight reduction. After the 9 month intervention, participants were categorized into self-monitoring groups (i.e. low, moderate and high) based on adherence to lifestyle self-monitoring during the intervention. Weight loss outcomes were then compared between groups. Participants who self-monitored at high levels lost significantly more weight (-9.0, 95% CI, -5.2 - -12.8%) than participants who self-monitored at moderate (-4.5, -8.0 - -1.1%) and low levels (0.0, -1.4 - 1.5%). For clinically significant (i.e. > 5%) weight loss, participants wore the electronic device on average 13 hours and 55 minutes per day, 80% of the time (i.e. 178 of 222 days) and tracked food consumption 47% of the time (i.e. 104 of 222 days) . To help reduce obesity levels health care professionals and scientists should promote high levels of lifestyle self-monitoring. Furthermore, more focus should be place on attaining and maintaining habitual physical activity and less on weight loss for mortality risk reduction.

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