想减肥,早吃饭

RENEE MONTAGNE, HOST: There's an old saying: It's best to eat breakfast like a king, lunch like a prince and dinner like a pauper. Now we have some evidence to back that up. NPR's Allison Aubrey reports on a new study that shows it's not what you eat, but when you eat it.

ALLISON AUBREY, BYLINE: The study's lead author is Marta Garaulet of the University of Murcia in Spain. And she recently made one change in the way she goes about eating. She has not scaled back on what she's eating. Instead, she's begun eating her main meal of the day a little earlier.

MARTA GARAULET: So, I have not been doing diet, but I realize that I am better now since I eat a little bit earlier.

AUBREY: And this fits with what her study showed. Garaulet said in Spain, it's quite common to skip breakfast and eat a big lunch, sometime in the early to mid-afternoon. Dinner is often very light. As a researcher, she was interested in knowing how the timing of these meals influenced weight loss. To evaluate this, she tracked about 400 overweight people living in her town, which is located on the coast of the Mediterranean Sea. All of them had volunteered to be part of a five-month weight loss trial, which required them to limit their calories. And at the end of the study, Garaulet found that the people who had eaten their main meal of the day early - before 3 p.m. - lost about five pounds more than those who ate later in the day, even though they were all eating about the same number of calories. Garaulet says it convinced her that the timing of a meal could make a big difference.

GARAULET: Of course, you know, when I got the result, it was the day that I change my schedule.

AUBREY: You started eating earlier.

GARAULET: Yes.

AUBREY: Researchers in the U.S., including Frank Scheer of Harvard Medical School, collaborated on the study. Scheer says they wanted to rule out other factors that might have explained the differences in weight loss between the early and late eaters. So they looked at things such as physical activity, hunger hormones, as well as sleep.

FRANK SCHEER: And none of these factors were significantly different between the two groups.

AUBREY: So what's at play here? Well, Scheer, who studies chronobiology, or how time influences biology, says recent animal studies have shown that the timing of eating can have a powerful influence on metabolism and weight regulation. This new study, he says, is among the first to suggest that this may also be true in people.

SCHEER: Only in recent years are we starting to try to tease apart what the underlying mechanisms might be.

AUBREY: In the study, the people who ate late and didn't lose as much weight also tended to skip breakfast, or eat just a little in the morning. And Scheer says that since eating seems to send a signal to our body clocks, it could be that when people delay eating until late in the day, things get out of whack. The master clock in the brain is no longer in sync with the mini-clocks in the cells of the body that regulate metabolism.

SCHEER: When the timing of meals doesn't match with the sleep-weight cycle well, there is a disconnect between the different clocks that we have in basically all the cells in our body.

AUBREY: And with this disconnect, the complex systems that regulate weight don't work as well. Now, not everyone is convinced by the findings of the study. Madeline Fernstrom of the University of Pittsburgh Medical School says she's skeptical that the timing of meals alone can influence weight so significantly.

MADELINE FERNSTROM: Clearly, there is something biological about this whole cascade. But I think there's a lot of other unanswered questions.

AUBREY: For instance, could it be that the amount of food at breakfast rather than the timing of lunch or dinner makes a difference? It's not clear. She says the more we learn about the many factors that may influence weight, it's important for dieters not to lose sight of the big picture.

FERNSTROM: The greater importance is what you are eating. You need to eat fewer calories and move more.

AUBREY: Which is, of course, something that you likely already know. Allison Aubrey, NPR News.