Eating induces thermogenesis, which can modulate circadian rhythm and wakefulness; eating early shifts the rhythm earlier, while eating late shifts it later.

“And that's because every time we eat we get eating induced thermogenesis regardless of what we eat. Now that eating induced thermogenesis and increase in metabolism, which is an increase in temperature really, is probably greatest for amino acid rich foods like meats, but also other types of foods.”

“if you're eating early in the day you're tending to shift your rhythm earlier. So that you'll want to wake up earlier the next day”

“And that's because every time we eat, we get eating-induced thermogenesis regardless of what we eat. And now you know from the discussion about temperature that if you're eating early in the day, you're tending to shift your rhythm earlier so that you'll want to wake up earlier the next day. If you're eating very late in the day, even if you can fall asleep after that, there's a tendency for you to want to sleep later the next day.”