When trying to lose weight, changing not just what you eat but when you eat may go a long way to help you reach your goals.
A new study shows that meal timing might affect how many pounds you can drop while you are dieting. The results were published on Jan. 29 in the International Journal of Obesity.
"This is the first large-scale prospective study to demonstrate that the timing of meals predicts weight-loss effectiveness," study author Frank Scheer, director of the Medical Chronobiology Program and associate neuroscientist at Brigham and Women's hospital, and an assistant professor of medicine at Harvard Medical School, said in a press release. "Our results indicate that late eaters displayed a slower weight-loss rate and lost significantly less weight than early eaters, suggesting that the timing of large meals could be an important factor in a weight loss program."
More than one-third of U.S. adults are obese with even more Americans overweight, increasing their risks for health problems including heart disease, stroke, Type 2 diabetes and certain types of cancer, the Centers for Disease Control and Prevention report.
Researchers studied a group of 420 overweight participants who were enrolled in a 20-week weight loss treatment in Spain. A person was designated as either an early eater or a late eater depending on the time they typically ate lunch. Early eaters ate lunch before 3 p.m., and late eaters ate after 3 p.m. In Spain, lunch is often the largest meal of the day, and participants' lunch accounted for about 40 percent of their daily calories.
After 20 weeks, early eaters lost about 22 pounds and late eaters lost 17, about 25 percent less weight loss than the earlier-eating group.
Late eaters were also more likely to eat fewer calories during breakfast or skip breakfast entirely. They also had a lower insulin sensitivity level, which is a risk factor for diabetes. Dinner and breakfast times had no influence on weight loss.
"This study emphasizes that the timing of food intake itself may play a significant role in weight regulation" lead author Marta Garaulet, professor of physiology at the University of Murcia Spain, said in a press release." She said weight loss treatments should incorporate not only calorie and nutrient intake, but should incorporate timing of meals.
Scheer told HealthDay that eating lunch earlier may affect the body's circadian rhythms, which play a role in the sleep-wake cycle and metabolism. Unusual mealtimes may disrupt the rhythm, he said, which could affect weight control. Since meal times differ in Spain, more research needs to be done to see if changing the time people sit down at the dinner table -- which tends to be the largest meal in the United States -- has an impact, he said.
But, changing your schedule might not be an easy feat.
"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, told TIME. "It's the same thing for eating. There are certain people where certain timing and patterns work for them."
Church suggested becoming more aware of times when you will be hungry, which normally fall around your usual breakfast, lunch and dinner meal times. Snacking desires also go up after dinner, he said, but a midnight snack can raise the body's temperature, blood glucose and insulin levels, interrupting the fat-burning process during sleep.
Elizabeth Ward, a registered dietitian in Boston and author of "MyPlate for Moms: How to Feed Yourself and Your Family Better," said to USA Today that no matter what the study shows, there's one way medical professionals know how to definitely drop pounds.
"(It's) an interesting study, but it's an observational study, so it doesn't prove cause and effect," she said. "If you cut back of your calories at any time of the day, you will lose weight."