Project Summary/Abstract: Older women are more likely than men to live with disease or disability that impairs activities for independent living and threatens quality of life. The mechanisms that broadly diminish health and well-being among aging women are not fully understood, but the transition into menopause at mid-life, and the ensuing decrease in circulating estrogens, is a particularly salient milestone in the female lifespan. Numerous studies document an association between the loss of ovarian hormones at menopause and the loss of their protective effects in domains of cognition, physical ability, and immune health. Estrogens typically act upon these systems to optimize cellular metabolism supported by mitochondrial oxidative phosphorylation. Loss of estrogens at middle-age is associated with increased oxidative stress and enhanced inflammatory responses. Hormone replacement therapy is prescribed to relieve signs and symptoms of menopause, but its broad actions carry undesirable and sometimes life-threatening risks. Identifying complementary strategies that restore the proper balance of metabolic and immune activities in peri- and post-menopausal women could decelerate age-related declines in cognitive, physical, and immune health without incurring risk for other age-associated diseases. The ketogenic diet may fulfill these criteria as consuming this high fat/low carbohydrate diet fundamentally alters metabolic profiles, shifting dependence away from glucose in favor of fat-derived ketone bodies, while also attenuating inflammation. Consistent with this view our preliminary data demonstrate that a ketogenic diet improved cognitive and mitochondrial function in aging female rats. The goal of this project is to elucidate the mechanisms by which the ketogenic diet decelerates age-related decline in multiple functional domains over the female lifespan. This project will use normally aging rats to 1) determine sex-specific effects of ketogenic diet on age-related decline of brain, muscle, and immune function and 2) determine protective effects of ketogenic diet on cognition, physical function, and immune profiles in surgically estrogen-deficient, middle-aged females. These studies of nutritional ketosis in well-controlled animal models of aging and menopause will be significant because they can provide the necessary mechanistic insights to guide the translation and development of appropriate dietary interventions that physicians can recommend as primary or adjuvant therapies to older women transitioning into menopause and at risk for age-related disorders. More broadly, identifying sex-specific and age-appropriate dietary guidelines to decelerate fundamental mechanisms that drive physiological and cellular aging will broadly improve health outcomes for older women and reduce reliance on hormone replacement therapy as a first-line treatment to combat symptoms of menopause. These objectives are within the scientific scope of the University of Sou...