> Fasting is the abstention from eating and sometimes drinking. From a purely physiological context, "fasting" may refer to the metabolic status of a person who has not eaten overnight (see "Breakfast"), or to the metabolic state achieved after complete digestion and absorption of a meal.[1] Metabolic changes in the fasting state begin after absorption of a meal (typically 3–5 hours after eating).

https://en.wikipedia.org/wiki/Fasting