Acute 1,3-Butanediol Co-Ingestion with Carbohydrate Does Not Improve Endurance Performance in Chronically Ketogenic Male Athletes

Nine recreationally active males with at least one year of ketogenic diet adherence completed a counterbalanced crossover study. They consumed either 60 g of carbohydrate (CHO) or 60 g of carbohydrate plus 0.5 g/kg of 1,3-butanediol (CHO + BD), then did a 60 minute set-intensity exercise bout followed by a 16.1 km time trial. Beta-hydroxybutyrate rose to 1.69 mmol/L post-exercise with CHO + BD versus 0.55 mmol/L with CHO (p < 0.001), and time trial times were 1606 s and 1620 s across the two conditions (p > 0.05). Glucose was lower at minutes 40 and 60 of set-intensity exercise with CHO + BD, and the authors note the small sample and limited statistical power.