Didn’t carbo-load before the race? Try some brains instead!
This is Sandra Tsing Loh with the Loh Down on Science.
Marathon runners rely on carbohydrates, like pasta, for energy. When that runs out, fat is next!
Now guess what’s sixty percent fat? Your brain! That’s due to the fatty myelin layer that coats nerve cells.
But does your brain’s own myelin get used as fuel during long runs?
Pedro Ramos-Cabrer and team from Basque Research scanned the brains of ten experienced runners – before and after a marathon.
Results? Post-marathon, myelin is reduced by nearly thirty percent in regions involved with motor coordination. But levels bounced back to normal within two months!
Wow! Your brain is incredibly adaptable! It may even be tougher than your Adidas!
Reference: Ramos-Cabrer, P., Cabrera-Zubizarreta, A., Padro, D. et al. Reversible reduction in brain myelin content upon marathon running. Nat Metab 7, 697–703 (2025). https://doi.org/10.1038/s42255-025-01244-7