It's beginning to look like a concept called TRF—or, time-restricted feeding—is going to be around for a while in the arena of diet and nutrition. The Washington Post has a feature on it, while the Wall Street Journal and others have covered it previously. The idea is surprisingly simple but backed up by a growing body of research: It's not so much what you eat as when you eat. More specifically, TRF suggests people should do all their eating in a 12-hour window, though research suggests they'll get more benefits if they can shrink that to, say, an eight-hour window. One of the lead researchers on the subject is Satchin Panda of the Salk Institute in San Diego, who thinks that humans aren't built to handle 24-hour access to food and the constant grazing that often results.
"If you're eating all the time, it messes up that pattern," he says of our circadian rhythm. His first studies on mice showed a range of health benefits—weight loss, less diabetes, etc.—and follow-up studies on humans seem to support the concept. Another researcher, Courtney Peterson of the University of Alabama, will report in a soon-to-be-published study that men diagnosed as pre-diabetic saw marked improvement after restricting their eating to between 8am and 2pm. Exactly how TRF results in benefits remains a little unclear, but in broad strokes, the body seems to better metabolize calories this way. "I think that within 10 years we will have some really clear guidelines for meal timing," says Peterson. "But we are in the early stages." Other researchers are more cautious, with one noting that it's "extraordinarily complex to actually nail this down." (Bad news on yo-yo dieting.)