Alternative medicine A period of voluntary abstinence from foods and/or drinks; fasting is integral to many religions, as it is believed to purify the mind and spirit; fasting rests the GI tract, and may rid the body of toxins and undigested metabolites; fasting leads to a loss of water, Na+, and K+, resulting in postural hypotension, and decreased blood sugar resulting in depression, …

fast· ing | \ ˈfas-tiŋ \ Medical Definition of fasting : of or taken from a fasting subject fasting blood sugar levels fasting urine also : occurring from or caused by fasting fasting hyperglycemia

Define fasting. fasting synonyms, fasting pronunciation, fasting translation, English dictionary definition of fasting. adj. fast·er , fast·est 1. Acting, moving, or capable of acting or moving quickly; swift. 2. a. Accomplished in relatively little time: a fast visit.

fasting. Fasting is going for a certain length of time without eating anything. Sometimes fasting is required before you have surgery, like getting your wisdom teeth removed. Often fasting is done for medical or health reasons, or in an attempt to lose weight. For many other people, fasting is an important part of their religious observance.