Today is Yom Kippur, the Jewish Day of Atonement. As is customary, I am observing the holiday by fasting for 24 hours. Supposedly, this self-denial will bring me closer to God and help me earn forgiveness for my sins. Needless to say, it’s pretty uncomfortable and most other days I eat to my heart’s content.
However, some people choose to fast for reasons other than eternal salvation. Caloric Restriction (CR) is a recent trend in which dieters limit their total calorie intake in order to improve their lifespan. Studies show that low calorie diets and intermittent fasting can significantly increase the lifespan of some animals and prevent the progression of neurodegenerative diseases like Alzheimer’s. CR has many critics, some of whom compare the practice to anorexia.
A new paper in the Journal of Neuroscience suggests that caloric restriction also improves baseline brain function. Fontan-Lozano et al. fed one group of mice ad libitum and another group of mice only on alternate days. They found that the mice subjected to intermittent fasting performed better on behavioral and electrophysiological measures of learning. This improvement was associated with upregulation of the NMDA receptor subunit NR2B and was reversed by application of a NR2B antagonist.
It is tempting to speculate about the evolutionary significance of fasting-induced cognitive enhancement. If food is rare in a given environment, then remembering how to access these limited resources would be an extremely adaptive trait.
It remains to be seen whether similar cognitive enhancement is observed in humans. If so, I may start observing Yom Kippur more frequently.