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In 1965, the American Physiological Society published an eight-hundred-page Handbook of Physiology dedicated to the latest research on adipose-tissue metabolism. As this volume documented, several fundamental facts about the relationship between fat and carbohydrate metabolism had become clear. First, the body will burn carbohydrates for fuel, as long as blood sugar is elevated and the reserve supply of carbohydrates stored as glycogen in the liver and muscles is not being depleted. As these carbohydrate reserves begin to be tapped, however, or if there’s a sudden demand for more energy, then the flow of fatty acids from the fat tissue into the circulation accelerates to take up the slack. Meanwhile, a significant portion of the carbohydrates we consume and all of the fat will be stored as fat in our fat cells before being used for fuel. It’s this stored fat, in the form of fatty acids, that will then provide from 50 to 70 percent of all the energy we expend over the course of a day. “Adipose tissue is no longer considered a static tissue,” wrote the Swiss physiologist Albert Renold, who coedited the Handbook of Physiology; “it is recognized as what it is: the major site of active regulation of energy storage and mobilization, one of the primary control mechanisms responsible for the survival of any given organism.” Since the excessive accumulation of fat in the fat tissue is the problem in obesity, we need to understand this primary control mechanism.
Gary Taubes in Good Calories, Bad CaloriesKindle Locations 7836-7847