Typical advice I've heard is to not stay hungry for too long. The stomach sends acid to the stomach as a strong message that it's hungry. Not eating means there

Typical advice I've heard is to not stay hungry for too long. The stomach sends acid to the stomach as a strong message that it's hungry. Not eating means there isn't food protecting the stomach from the acid. That risks getting an ulcer. Fasting seems to be a common practice, though. I wonder what variations in fasting (how long to go without eating, how often to fast, etc.) maximizes fasting time while keeping the risk of getting an ulcer to a minimum. EDIT: Changed "increases or decreases risk" as of course fasting is not going to decrease the risk as opposed to not fasting.