By 2030 it estimated that 20% of individuals in the United States (U.S.) will be 65 years of age or older, indicating a shift in demographics over the past century. The aging process is strongly associated with reduced aerobic capacity and functional performance as well as increases in inflammation and oxidative stress. With differences in the demographic profile, eating patterns have also changed for Americans within the past 30 years, with a majority of Americans consuming at least one snack/day; with the types of snacks consumed being processed foods that are high in refined carbohydrates, saturated fats, and low in fiber. Additionally, the aging process contributes to decreases in RMR, which can promote alterations in body composition. Lifestyle modifications have been shown to contribute to beneficial outcomes associated with aging. Therefore, healthy, nutrient-dense foods are of primary importance for enhancing functional performance, aerobic capacity, and physical activity as well as improving vascular function, body composition, and markers of inflammation/oxidative stress within this growing population. Tree nuts are a nutrient- and energy dense food, which may contribute to increases in RMR due to their high amounts of poly- and monounsaturated fatty acids affecting diet-induced thermogenesis. Almonds (Prunus dulcis) are an excellent source of α-tocopherol and a good source of monounsaturated fat, magnesium, fiber, and protein. When compared to other nuts almonds have the greatest amount of fiber and protein. Almond supplementation has been shown to attenuate age-related decline in aerobic fitness and physical performance measures. Few studies have assessed how almonds alone affect fitness and physical function. However, Yi et al. found that in young healthy, endurance trained individuals, consumption of almonds elevated serum arginine, nitric oxide and TAC, all of which contributed to improved exercise performance. Constituents of almonds including L-arginine and magnesium have been shown to increase anaerobic threshold and physical performance in healthy active older adults respectively . Studies have found that the incorporation of almonds in a diet can decrease oxidative stress and improve vascular function. Improvements in both FMD and systolic blood pressure were shown after 4 weeks of almond consumption in healthy old and young men. L-arginine, an amino acid vital for synthesis of nitric oxide, which controls vascular tone, is also found in almonds. Almonds are often cited as a healthy, protein-boosting snack, beneficial for sustaining muscle mass and metabolism, without increasing fat mass or total energy intake. Additionally, studies have demonstrated that body weight and body mass index (BMI) remain unchanged during almond supplementation interventions. Almond consumption has also been shown to decrease visceral fat and body fat percentage. The extent to which daily almond consumption affects functional performance, aerobic capacity, energy expenditure, vascular function, body composition and inflammation/oxidative stress in active overweight and obese older adults needs to be investigated.

For this study, fifty men and postmenopausal women will follow a randomized-controlled crossover design. If individuals qualify for participation after the screening visit, they will be asked to complete a 3-day food record and wear an ActiGraph to track physical activity and sleeping patterns for the next seven days, to be returned at their Baseline Study Visit #1. During the Baseline Study Visit #1 assessments of: RMR, body composition (DXA), vascular assessments (FMD, PWV, PWA, blood pressure), heart rate, anthropometrics (height, weight, and waist/hip circumference), venous blood draw, POMS, and sleep quality (PSQI) will be collected. The following day, participants will return for their Baseline Physical Performance Visit #1 to complete assessments of submaximal aerobic capacity and the CS-PFP. Following this visit, participants will be provided with 12 weeks of almonds or the isocaloric snack. Participants will be asked to come in after 6 weeks to receive the rest of their dietary regimen and to monitor compliance. During week 11, participants will be asked to come to the study site to be given a 3-day food record and the ActiGraph to be retuned at the Post-Test Study Visit #1. After 12 weeks, participants will return to FSU to complete their Post-Test Study Visit #1, which will involve all the same assessments from the baseline study visit, as well as their Post-Test Physical Performance Visit #1, the next day. After the 4-week washout period, participants will similarly be asked to complete a 3-day food record and wear an ActiGraph for the following 7 days, to be returned upon the participants' Baseline Study Visit #2, where participants will crossover into receiving the corresponding dietary regimen and will follow the same procedures for the following 12 weeks. Participants will be compensated a total of $200 if the entire study is completed.