Fasting is simply the restriction of food for an amount of time. This restriction can range anywhere between 16 hours to several days or longer. There are several different types of fasting including intermittent fasting, fat fasting, alternate days fasting, extended fasting, and dry fasting.
Intermittent fasting (IF): This type of fasting is characterized by alternating between periods of fasting and feeding. One common protocol for IF is 16:8. In this example you would fast for 16 hours (example: 8pm-12pm) and eat for 8 hours (example: 12pm-8pm).
Fat Fasting: Fat fasting is characterized by only consuming calories from fat for an extended period of time. This ensures you stay in a state of ketosis, which mimics your bodies response to fasting. This type of fasting is often beneficial for fasting beginners because the satiety effect of eating fat or for those looking to get more calories in their diet or stimulate greater brain performance.
Alternate Day Fasting: This method of fasting involves fasting for a few days each week. For example you could fast every sunday and thursday and eat normally the other days. Another variation of alternate day fasting is to consume ¼ of your normal caloric intake on the two fasting days.
Extended Fasting: This method fasting involves fasting for 48 hours or longer. This type of fasting can be done every few months.
Dry Fasting: All of the above fasting methods allow for water, black coffee, and tea to be consumed during the fast. Dry fasting involves not eating or drinking during the fast. This type of fasting in more controversial and may lead to dehydration.