Diet is a topic of concern among many Americans today. Research has shown that what we eat can have an impact on our overall health and mental health, particularly anxiety. However, the majority of laboratory studies examining the relationship between diet and mental health are usually conducted on younger animals, while in the human population individuals often adopt new dietary regimens later in life, particularly after experiencing adverse health outcomes. Thus, if significant associations exist between mental health and diet, it is of utmost importance to investigate these effects in an aged population. In this study we will use 90 one-year old male Sprague-Dawley rats weighing between 500 grams to 600 grams, divided at random into three different dietary groups: a high-fat group (45% saturated fat), a high-sucrose group (35% sucrose), and a control group. An open-field test, used to measure anxiety levels, will be conducted at three different time points for each group: baseline (day 1), re-test 1 (day 21), and re-test 2 (day 42). After the assessment of the initial 21-day period of being on specialized diets (re-test 1), they will be switched back to a standard diet to assess anxiety levels after dietary changes (re-test 2). A mixed factor analysis of variance will be conducted. The implications of this study are crucial for the aging population because it provides needed data on the effect of diet on mental health in older adults. These findings may be used to guide nutritional choices in the elderly, particularly in institutional settings (i.e., nursing homes).