How do organisms make dietary choices?

When given a choice, organisms will choose a diet that maintains a nutritional balance in tune with their needs. That choice, studied in fruit flies for the first time, is regulated by activity in a molecular pathway involved in aging, cancer and diabetes. Humans share the same molecular pathway. The study, the first to be done in a genetically tractable lab animal, could lead to treatments that would “reboot” metabolic pathways in individuals who are obese or suffer from diabetes.