Detectors in the liver that signal lipoprivic hunger appear to be sensitive to changes in their own internal rate of metabolism. Using a pyloric cuff, researchers demonstrated that the volume of stomach contents is more important than its nutritive content for satiety. By injecting glucose and fructose into the hepatic portal vein, researchers confirmed that the liver contains receptors that respond when the liver receives nutrients from the intestines. If ob mice are given an injection of leptin they lose weight rapidly because they develop diabetes and cannot metabolize glucose. Fenfluramine, a drug that helps obese people loose weight, stimulates the release of neuropeptide Y. insulin.
Anorexics are unresponsive to the effects of food.