After noticing the tendency of shift workers to be overweight,a team of researchers from Northwestern University decided to investigate whether eating at times that conflict with bodys natural circadian rhythms could be contributing to weight gain.
Press Release (PressBurner) Sep 10, 2009 - When Leonard Maltin, well-known American film critic and film historian, said “Timing in life is everything,” he was referring to the timing of his breakthrough into writing. But the importance of being able to judge when to do or say something in order to get the best effect can be seen in almost every aspect of life. For example, consumers could save a great deal of money by waiting to purchase real estate until prices and mortgage rates are especially attractive, or by timing the purchase of a car to when dealers are offering particularly good prices. The same concept can be applied to playing an instrument or hitting a ball in a sport. And, according to a new study, choosing the right time to eat could make a difference in the amount of weight we gain.
After noticing the tendency of shift workers to be overweight, a team of researchers from Northwestern University decided to investigate whether eating at times that conflict with the body’s natural circadian rhythms could be contributing to weight gain. They conducted an experiment on two groups of lab mice; both groups were fed a high-fat diet containing the same number of calories and both had about the same amount of exercise. The difference came in the timing of their meals; one group was fed at night, which is the normal feeding time for mice since they are nocturnal, while the other group was fed during the day, which would be their normal resting time.
After six weeks, the mice fed at the “right” time had a 20 percent gain in their body weight, but the mice fed at the “wrong” time had a 48 percent gain. The wrong-time group also gained about 8 percent more body fat than the right-time feeders. Study co-author Fred Turek, professor of neurobiology and physiology in the Weinberg College of Arts and Sciences and director of Northwestern’s Center for Sleep and Circadian Biology, said the findings seem to show there really is a “wrong” time to eat. “How or why a person gains weight is very complicated, but it clearly is not just calories in and calories out,” he said in a statement. “Better timing of meals, which would require a change in behavior, could be a critical element in slowing the ever-increasing incidence of obesity.”
Tam Fry, from the National Obesity Forum, agrees. “It is groundbreaking. It really gets you thinking why this has not been done before,” he said. “It could be very dramatic if it affects whether you are going to get fat or not.”
The researchers suggest eating late at night, when our body says we should be sleeping, disrupts our circadian rhythm, or internal clock, which governs not only our sleep cycles but feeding and activity cycles as well. A 2006 Institute of Medicine report that reviewed the body of research on sleep concluded that “addressing obesity will likely benefit sleep disorders, and treating sleep deprivation and sleep disorders may benefit individuals with obesity.”
“I think sleep has a very important role in metabolism,” said Deanna Arble, a neuroscientist at Northwestern and the study’s lead author. “While I do not believe the field is advanced enough to prescribe appropriate eating times for each individual, I believe we can at least say that humans should avoid eating during their normal sleeping phase because this could lead to increased weight gain.”
But Arble says it is also important not to lose sight of the importance of total caloric intake. “If you are taking in excess calories daily, the time you eat probably doesn’t matter—you will still gain weight,” she said. “Similarly, if by eating small meals for dinner you decrease your overall caloric intake, that could be more beneficial than timing.” She advises, however, that “for someone not consuming excess calories each day, and they’re doing everything by the book but still gain weight, maybe look into the time of day you’re eating. It could be a factor.”