Do the calories you consume earlier in the day cause you to put on less weight than those you consume later on? That’s long been a matter of debate, but new research suggests that meal timing may play a role in determining a person’s body weight.
Researchers from Boston and Spain gave 420 overweight Spaniards a Mediterranean-style eating plan—based on fresh produce, legumes, fish, and whole grains—to help them lose weight; after 20 weeks, they found that those who ate their biggest meal earlier in the day lost about 25 percent more weight than those who ate it later in the day, according to the study published in the International Journal of Obesity.
While the amount of calories consumed and burned throughout the day didn’t differ significantly among the early and late eaters, the early eaters lost 22 pounds compared with 16.5 pounds for the late eaters.
“It was really the timing of lunch that was the main factor that determined how successful dieters were,” said study co-author Frank Scheer, director of the medical chronobiology program at Brigham and Women’s Hospital. The timing of the smaller breakfast and dinner didn’t seem to make a difference in the amount of pounds lost.
I should note here that, as is the custom in Spain and several other European countries, lunch was the biggest meal of the day; it comprised about 40 percent of total daily calories—with about half the study participants (the early eaters) consuming this meal before 3 p.m. and the other half (the late eaters) consuming their lunch meal after that time.
Whether these findings apply to American-style eating habits with a light breakfast and lunch followed by a hearty dinner and late-night snacking remains unknown, Scheer said, though it may be a wise move to aim for an earlier dinner and to skip the before-bed munch fest.
“I think there’s something to this,” said Joan Salge Blake, a registered dietitian at Boston University’s Sargent College of Health and Rehabilitation Sciences who writes boston.com’s Nutrition and You blog. “I’ve seen this in my practice a gazillion times where my patients eat like a triangle, increasing their calories as the day goes on when they should be cutting back at night.”
Nighttime noshing causes weight gain for a lot of folks, likely due to an overconsumption of calories. But Scheer believes that the body’s natural circadian rhythms may also be playing a role in how those calories are handled—whether they’re quickly metabolized and burned off by the body or shuttled away into fat cells for storage.
“Animal studies suggest that the liver tends to be more active at a certain time earlier in the day,” Scheer explained. If mice or rats are fed most of their calories during that time, they gain less weight compared with when they are fed at later times. Whether this applies to humans remains unknown but Scheer said it adds strength to the saying that we should eat like kings at breakfast and paupers at dinner.
“Why not try it?” Salge Blake said, “I don’t think we need to wait for the mechanism to be known since there’s no harm in eating a bigger meal for lunch and lighter meal for dinner.”
At the very least, it will help you avoid sleep-disrupting indigestion that often occurs in those who go to bed soon after eating a heavy meal.