Electronic Theses and Dissertations

Date of Award


Document Type


Degree Name

Ph.D. in Nutrition and Hospitality Management

First Advisor

Teresa Carithers

Second Advisor

Melinda Valliant

Third Advisor

Kathy Knight

Relational Format



Obesity in older adults is a public health challenge in the United States and many regions of the world. This study analyzed data from the National Health and Nutrition Examination Survey (NHANES) ranging between 2005-2006 to 2017-2018 to examine associations between lifestyle behaviors and obesity, and identify trends and contributions of lifestyle behaviors in older adults. A total of 5,812 participants in a body mass index (BMI)- based obesity group and 5,655 participants in a waist circumference (WC)-based obesity group were selected for association and trend analyses. Logistic regression was applied to estimate the associations between lifestyle behaviors and obesity. Tests for trends of significant lifestyle behaviors across seven cycles were evaluated using orthogonal polynomial coefficients in a regression analysis. Students’ t-test was used for comparing the slope of obesity trends and the slope of significant lifestyle behaviors trends. A total of 1,461 participants in both BMI-based and WC-based obesity groups were selected for Oaxaca-Blinder regression decomposition analysis to detect how much obesity change could be explained by the lifestyle behaviors in 2017-2018, compared to 2005-2006. Logistic regression showed that significant lifestyle behaviors related to obesity were total sugar intake, dietary fiber intake, protein intake, food away from home, three intensities of physical activity, alcohol consumption (moderate), smoking (heavy), sleep problem (nearly every day), and intentional weight loss. Among these significant lifestyle behaviors, trends of total sugar intake and heavy smoking behaviors were significantly different from the BMI- based obesity trend. The rest of lifestyle behaviors were similar to the trends of BMI-based and WC-based obesity. Lifestyle behaviors explained half of the increase in obesity from 2005 to 2018. These findings provide important guidance on targeting interventions related to lifestyle behaviors that might be effective in reducing the high prevalence of obesity in older adults.



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