Ketone ester ingestion increases exogenous carbohydrate storage and lowers glycemia during post-exercise recovery; A randomised crossover trial.

β-hydroxybutyrate can suppress endogenous glucose production, with potential implications for carbohydrate metabolism during post-exercise recovery. The aim of the current study was to assess the effects of ketone ester ingestion during post-exercise recovery, on carbohydrate metabolism and subsequent exercise capacity. Thirteen endurance-trained men completed two conditions in a randomised crossover design. During both conditions, participants performed two exhaustive bouts of running separated by 4 hours of recovery, during which they ingested sucrose (1 g.kg ^− 1 .h ^− 1 and high natural abundance ¹³ C) and whey protein (0.4 g·kg ^− 1 ·h ^− 1 ) beverages. In one condition, the beverage was supplemented with 0.29 g·kg ^− 1 ·h ^− 1 of ketone monoester (KETONE), in the other, the beverage was supplemented with an isoenergetic (fat), taste-matched placebo (PLACEBO). Breath samples were analysed for CO ₂ production and ¹³ C enrichment to determine the fate of ingested carbohydrate. Blood was sampled to examine metabolite and insulin concentrations. KETONE increased blood β-hydroxybutyrate concentrations (> 3.5 mmol·L ^− 1 versus PLACEBO, p  < 0.0001) and retention of ingested sucrose (from 206 ± 26 g with PLACEBO to 220 ± 26 g with KETONE, p  = 0.001) while lowering glycemia (> 1 mmol·L ^− 1 versus PLACEBO, p  < 0.0001). This occurred with no evidence of increased gastrointestinal distress during recovery, but mild additional lower gastrointestinal distress during the second run ( p  = 0.03). There was no evidence for differences in time-to-exhaustion during the second run (PLACEBO:54 ± 33 minutes, KETONE:52 ± 28 minutes; p  = 0.87). In conclusion, ketone ester ingestion during post-exercise recovery augments retention of ingested carbohydrates and lowers glycemia. No evidence for increased exercise capacity was detected during subsequent running.