Wiktionary(1.00 / 1 vote)Rate this definition: quantity(Noun) A fundamental, generic term used when referring to the measurement (count, amount) of a scalar, vector, number of items or to some other way of denominating the value of a collection or group of items. You have to choose between quantity and quality.
When the body is making and using ketones we say that the body is in a state of ketosis. Ketosis begins after about 48 hours (2 days) or water fast for women, or about 72 hours (3 days) of water fast for men.
It involves the body producing ketone bodies out of fat, and using them for energy instead of carbs. You can get into ketosis by following a very low-carb, high-fat ketogenic diet (1). In addition to fast weight loss, ketosis may have several health benefits, such as reduced seizures in epileptic children (2).