(R)(R)Use of a ketone body and a ketone body ester for preserving glycogen and/or protein thereby reducing muscle breakdown and improving endurance during exercise and promoting muscle recovery following exercise. Also for retarding muscle wasting in aging and disease. 3 hydroxybutyl 3 hydroxybutyrate for use in reducing muscle glycogen and protein breakdown during exercise or decreasing muscle wasting in aging and disease. Certain esters of hydroxybutyrate monomers particularly a monoester of D hydroxybutyrate with R 1 3 butanediol or with glycerol to reduce muscle breakdown and aid muscle recovery after exercise or retard muscle wasting. Compositions containing the ketone bodies or ketone body esters are also described.
