Notably, traveling east is often harder on the body than traveling west, as Kopp often experienced herself, because it forces the body to sleep earlier than it’s accustomed to; conversely, traveling west is generally easier to adapt to.

Kopp’s approach, while it hasn’t been formally studied, does align with some emerging research on circadian biology. Fasting during travel and delaying the first meal until arrival may help shift the body’s “food clock,” a secondary circadian system that responds to eating times. And studies suggest meal timing can influence how quickly the body adjusts to a new time zone: Some experts recommend eating only light meals during flights, but then doing activities in your local time zone like eating and sleeping as soon as you arrive, to help reset internal rhythms.