fast·ing 'fas-tiŋ adj of or taken from a fasting subject <\fasting blood sugar levels> <\fasting urine> also occurring from or caused by fasting <\fasting hyperglycemia>
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fast·ing (fastґing) abstinence from all food and drink except water for a prescribed period, performed for both spiritual and therapeutic purposes; among its uses is as a means of detoxification, def. 3 (q.v.).Medical dictionary. 2011.