Precision Medicine and Physical Function

The investigators aim to conduct a 12-week, single-arm, pre/post-intervention of b-hydroxy-methylbutyrate in persons aged 65 to 85 years to assess feasibility and acceptability of the intervention and study procedures, secondary outcomes of physical function and changes in multi-omics patterns, and exploratory outcomes that will allow the team to describe physical function phenotype. The investigators' primary outcomes are the: feasibility of the study procedures (including safety), feasibility of the intervention delivery, and acceptability of study procedures and measures. Secondary outcomes include: Objective and subjective physical function measures that predict disability including the 30-second sit-to-stand, knee strength, isokinetic strength, grip strength, gait speed, 400-m walk test, Pittsburgh Fatiguability, PROMIS global health-10, social support, anthropometry, National Institutes of Health (NIH) Cognitive toolbox, Automated Self-Administered 24-hour Dietary Assessment (ASA-24), Community Healthy Activities Model Programs (CHAMPS), Ultrasound Imaging, Magnetic Resonance Imaging (MRI), Changes in untargeted metabolomic profile data based on qualitative or semiquantitative analysis of the most probable detectable metabolites in laboratory samples , Discover potential metabolites that explain changes in physical function using a discovery science, precision medicine approach (discovery science approach that is exploratory)