Ketogenic compositions including a non-racemic mixture of beta-hydroxybutyrate (BHB) enriched with the S-enantiomer are formulated to control ketone body levels in a subject. The non-racemic mixture of BHB is enriched with the S-enantiomer to modulate the effect of ketone bodies in the subject and control the rate at which ketosis is achieved. In some aspects a composition for controlling ketone body level in a subject contains a dietetically or pharmaceutically acceptable carrier and a non-racemic mixture of S-beta-hydroxybutyrate and R-beta-hydroxybutyrate, wherein the non-racemic mixture contains from about 52% to 99% by enantiomeric equivalents of S-beta-hydroxybutyrate enantiomer and from about 48% to about 1% by enantiomeric equivalents of R-beta-hydroxybutyrate enantiomer.