Acute Ketogenic Diet and Ketone Ester Supplementation Impairs Race Walk Performance

Consumption of a ketogenic low-carbohydrate (CHO), high-fat (LCHF) diet increases skeletal muscle fat utilization but impairs exercise economy. Whether the concomitant increase in circulating endogenous ketone bodies (KB) alters the capacity to metabolize exogenous ketone supplements such as the popular ketone monoester (KE) is unknown. PURPOSETo determine if LCHF and KE supplementation can synergistically alter exercise metabolism and improve performance. METHODSElite race walkers (n=18, 15 male, 3 female; V[Combining Dot Above]O2peak 62 ± 6 mL·min·kg) undertook a 4-stage exercise economy test and real-life 10,000 m race prior to and following a 5-d isoenergetic high CHO (HCHO; ~60-65% CHO, 20% fat; n=9) or LCHF (75-80% fat,