RecruitingClinical trialTargeting Aging With a Ketone Ester for Function in FrailtyThis study aims to find out if a food supplement that contains a naturally occurring substance, ketones, can help to improve strength and general wellness in adults at, or over the age of 65 years who are experiencing a slight decline in their physical function. Participation will involve a screening visit and 4 additional study visits over the course of 20 weeks. After being assessed for eligibility, study participants will be sorted into two groups at random and consume either a ketone or placebo supplement at home every day for 20 weeks. Both study products can cause gastro-intestinal side effects in some individuals. At all study visits, subjects will provide blood samples. At three study visits, subjects will be asked to complete physical performance tests, provide blood, stool and urine samples. They will also complete questionnaires during three study visits to assess physical function, markers of inflammation, and other aspects of general well-being. The study enrolls at three sites across the United States, in California (Buck Institute), Ohio (Ohio State University), and Connecticut (University of Connecticut). The study is coordinated by the San Francisco Coordinating Center (California Pacific Medical Center).