Turns out that the old adage “Eat breakfast like a king, lunch like a prince, and dinner like a pauper” may have some truth to it. A Spanish study published in the International Journal of Obesity adds to the mounting evidence that it’s best not to eat too much late in the day. The study found that dieters who ate their main meal before 3 p.m. lost significantly more weight than those who ate later in the day. This was true even though the early eaters ate the same number of calories as the later diners. The former group also had lower estimated insulin sensitivity; this is a risk factor for diabetes. This is the first large-scale study to suggest that timing may also be an important part of weight loss, along with how much you eat and how much you burn off.
The study focused on 420 overweight and obese participants over five months in the seaside town of Murica, Spain. Over that time period, people in the late-eater group lost much less weight than the early-eater group. They were also more likely to skip breakfast or to eat lower-calorie breakfast than their counterparts. However, the groups were about equal in all other areas the researcher tested for, including total daily calories consumed and expended, levels of appetite hormones, and sleep duration. On average, the early eaters lost 22 pounds compared with the late-eater who lost 17 pounds.
“The study suggests that it’s not just what we eat but when we eat is important,” says study author Frank Scheer, who directs the Medical Chronobiology Program at Brigham and Women’s Hospital in Boston. He says that eating seems to send a signal to our body-clocks; it’s possible that when we eater later, it sends our body clock out of whack and cause our body to metabolize food less efficiently. “When the timing of meals do not match with the sleep-wake cycle well, there’s a disconnect between the different clocks that we have in basically all the cells of our body,” explains Scheer.
However, Scheer cautions that weight loss is complicated. The total amount of calories you’re eating and burning off ever is still the most important factor in weight loss. And, of course, we already knew that.