<p>  </p> <p>Food insecurity describes the lack of access to foods and affects 10.2% of general U.S. households and 27% of low-income households in 2021. Food insecurity is a pervasive public health concern in the United States and has been linked to poor dietary intake and diet quality, overweight and obesity (especially among women), and risk of other chronic diseases, such as diabetes, hypertension and dyslipidemia. </p> <p>To better understand food security status and address its associated health and dietary outcomes among low-income populations, a conceptualized model was built and served as research framework for the dissertation, including 1) internal factors and motivations, such as traits related to self-efficacy and sufficiency that may influence diet and health; 2) external factors of temporary support, such as financial benefits from assistance programs that low-income populations are eligible for that may influence diet and health; and 3) external factors of potentially long-term support, such as nutrition education programs targeting low-income groups that may foster internalized knowledge that could sustain impact and improvement of diet and health in the long-term. Each chapter of this dissertation addresses a component of the model.</p> <p>Cross-sectional analysis of a sample of rural veterans using food pantries quantified psychological traits related to self-motivation and efficacy including grit and help seeking, at the individual and internal factors level of the conceptualized model, and their links to food security and resource use, and revealed an inverse association between grit score and risk of food insecurity. The findings provided evidence for future interventions targeting food insecurity improvement to include education and resources that address traits related to self-efficacy, such as grit, among low-income populations to improve health outcomes directly or through improving food security or use of resources. </p> <p>Using nationally representative data, the second study investigated relationships between food assistance through the Supplemental Nutrition Assistance Program (SNAP) participation, a type of societal level external support, and dietary outcomes among low-income older U.S. adults. There were no differences in dietary quality, usual nutrient intake or risk of inadequacy between SNAP participants and eligible nonparticipants. Furthermore, results revealed a high prevalence of not meeting the Estimated Average Requirement from dietary sources for several nutrients (vitamins A, C, D, E, calcium, and magnesium) but the prevalence was lower when nutrients from dietary supplements were included. The results highlight a need for continued effort to improve nutrient and dietary intake among low-income older adults.</p> <p>External factors of potentially long-term support (e.g. nutrition education and food assistance) were evaluated for relationships with body mass index. A longitudinal sample of low-income women interested in participating in nutrition education through SNAP-Education (SNAP-Ed) was examined to determine the relationship between nutrition education (SNAP-Ed) and food assistance program participation through (SNAP, WIC), separately and in combination, with long-term changes in body mass index. No differences in changes of weight status over time were observed by nutrition education, food assistance, or combination participation. The prevalence of obesity was high among this sample, calling for targeted obesity prevention interventions and further support of healthy lifestyle promotion among low-income populations. </p> <p>The findings shown in this dissertation further reveal a high health burden among low-income groups. The studies filled several research gaps described in the conceptualized model. The results may be used to inform future tailored interventions to address food insecurity, dietary and health outcomes at individual and societal levels, incorporating internal motivation and external support to mediate health and dietary risks among low-income population.</p>