BETHESDA, Md. (AP) — Sam Srisatta, a 20-year-old Florida college student, spent a month living inside a government hospital here last fall, playing video games and allowing scientists to document every morsel of food that went into his mouth. From big bowls of salad to platters of meatballs and spaghetti sauce, Srisatta noshed his way through a nutrition study aimed at understanding the health effects of ultraprocessed foods, the controversial fare that now accounts for more than 70% of the U.S. food supply.