[He's impressed by how quickly she downed her serving.]

Sometimes they last a little longer, or they vanish earlier than a week. I've seen people affected by experiments lasting as little as a few hours, but never anything more than maybe ten days. One week is usually just the meterstick we set things by.

They sometimes don't happen in a month... or if they do, they're so subtle no one notices.

Help yourself to some more if you're still hungry, by the way.