Burke 2021, Ketogenic LCHF diet: the future of elite endurance sport?

J Physiol 599(3):819-843, DOI 10.1113/JP278928. Review of the LCHF evidence in elite endurance sport. Confirms substantial increases in muscle fat oxidation within days to weeks of adaptation (up to ~1.5 g/min, with peak oxidation shifting toward ~70% of maximal aerobic capacity), but concludes that the impaired ability to use available glycogen limits higher-intensity endurance performance. Notes wide between-individual variability in response. Balanced verdict from the field’s leading critic. Moderate-to-strong.