The body\'s natural marijuana-like chemicals may be the reason why people find it hard to eat only one potato chip or one french fry, U.S. researchers say. Daniele Piomelli and Nicholas DiPatrizio of the University of California, Irvine, and colleagues found the fat in these foods trigger a biological mechanism that likely drives gluttonous behavior. The research team discovered that when rats tasted something fatty, cells in their upper gut started producing endocannabinoids natural marijuana-like chemicals in the body but sugars and proteins did not have the effect. When the tongue tastes fat in food it generate a signal that travels first to the brain and then through a nerve bundle called the vagus to the intestines, where the signal stimulates production of endocannabinoids, which initiates a surge in cell signaling that prompts the wanton intake of fatty foods, Piomelli explains. This initiates the release of digestive chemicals linked to hunger and satiety that compel people to eat more, the study says. Piomelli says, from an evolutionary standpoint, there\'s a compelling need for animals to consume fats, which are scarce in nature but crucial for cell functioning. However, in today\'s world, fats are readily available and the innate drive to eat fatty foods leads to obesity, diabetes and cancer. The findings are published in the online edition of Proceedings of the National Academy of Sciences.