For Weight Loss Success, Think About When, Not Just What, You Eat

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January 30th, 2013

By Alexandra Sifferlin

Timing is everything for losing weight .

In the latest collaborative study, researchers at the Brigham and Women’s Hospital, Tufts University and the University of Murcia in Spain, found that the time of day you eat large meals may help to predict how many pounds you drop.

In a study published in the International Journal of Obesity, the scientists monitored 420 overweight participants on a 20-week weight loss program in Spain. The volunteers were split into two groups: early-eaters and late-eaters. Since lunch is considered the largest meal in Spain–about 40% of the day’s calories are consumed in the mid-day meal–half the participants ate lunch before 3 p.m. while the remainder ate lunch after 3 p.m.

The late-eaters lost less weight overall, and shed pounds at a slower rate than those eating earlier. Those eating lunch later were more likely to skip breakfast or eat fewer calories, while the timing of breakfast and dinner didn’t influence weight loss effectiveness for either group. The researchers also considered other factors such as total caloric intake, energy expenditure, the appetite hormones leptin and ghrelin, and amount of sleep, but found they were similar in both groups.

“The timing of the main meal by itself seems to be the most determinant factor in weight loss effectiveness, and therefore eating at the right time may be a relevant factor to consider in weight loss therapies,” the authors write. They acknowledge that other factors may still explain the faster weight loss among the late eaters, such as genetics and how much each group slept on average, but the timing of the day’s largest meal was still worth considering as an important contributor to weight.

The findings support weight loss advice that suggests eating the biggest meal of the day earlier, which increases the chances that you can burn off the calories you take in. As simple as it sounds, however, changing the timing of meals may not be easy for everyone. “Some people like to exercise at four in the morning. I don’t get it, but it works for them,” says Dr. Tim Church, director of the Laboratory of Preventive Medicine at the Pennington Biomedical Research Center in Baton Rouge, Louisiana, who is unaffiliated with the study. “It’s the same thing for eating. There are certain people where certain timing and patterns work for them.”

To maintain healthy weight, it’s also important to eat when you are hungry, and not just in response to food cravings. “Hunger peaks when you expect it to peak at breakfast, lunch and dinner. Cravings peak after dinner,” he says. But eating late at night can raise body temperature as well as blood glucose and insulin levels, which disrupts the fat-burning that generally occurs during sleep. Timing meals, especially the heaviest meals, can make a difference in whether calories are processed into extra pounds or burned away.

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