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.
When you go on a ketogenic diet, your body almost solely runs on fat. Your insulin levels become rather low as well. Since you are burning so much fat, this is a great way to lose weight. Studies show that ketogenic diets result in greater weight loss. The fastest way to get into ketosis is by fasting. However, you cannot fast for very long, so you need to start a low carb diet.