Study Shows Mealtimes Alter Circadian Rhythms and Body Weight

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Study Shows Mealtimes Alter Circadian Rhythms and Body Weight

New research on mice supports the notion that eating at the wrong time can severely affect a person’s circadian rhythms and their ability to lose weight. It is possible that the time one eats can be even more important than what is being eaten.

The study, conducted at the University of Texas Southwestern Medical Center, used a high-precision feeding system on lab mice to dictate when the mice ate each day. Only mice who ate during their normal active time of day and feeding time lost any weight. None of the other four groups was able to lose any weight while eating during abnormal times. Even the group which ate the same amount of food as the first failed to reach the same results.

“Translated into human behavior, these studies suggest that dieting will only be effective if calories are consumed during the daytime when we are awake and active. They further suggest that eating at the wrong time at night will not lead to weight loss even when dieting,” noted Chairman of Neuroscience at UT Southwestern’s Peter O’Donnell Jr. Brain Institute and Investigator with the Howard Hughes Medical Institute Dr. Joseph S. Takahashi.

For humans, this means that the beloved midnight snack may be doing more to hurt diets and stave off weight loss than previously understood. While many people believed they could skirt the issue by opting for fruit or a vegetable in the evening, simply indulging before bed, regardless of the chosen food, could undo hard work during the day.

It might also keep you awake. Two groups of mice had their food delivered at unusual times during their normal day-night cycle and were found restlessly active when night fell. The researchers believe they have developed chronic sleep deprivation as a result of the mistimed feeding. One of these groups had a dietary restriction 30 percent less than their normal caloric intake while the other group enjoyed unlimited food access.

On the opposite end of the spectrum, some of the mice on a reduced diet ate their food rapidly over a short duration of time and were found to be surprisingly active during their natural resting daylight hours. The mice were found to have their clocks flipped around by the time they were fed and how much they had to eat. This suggests that we may be dictated by our meal routines far more than most people understand.

In their study’s summary, the scientists working on the experiment describe theirs as a “system that controls duration, amount, and timing of food availability and records feeding and voluntary wheel-running activity in mice. Using this system, mice were exposed to temporal or caloric restriction protocols.” the system enabled them to tightly regulate how much and when their lab mice were eating each day. They found this is to bar less “labor intensive” and “imprecise” than traditional dietary restriction protocols used in other experiments.

The summary also points out that “Mice under CR self-imposed a temporal component by consolidating food intake and unexpectedly increasing wheel-running activity during the rest phase, revealing previously unrecognized relationships among feeding, metabolism, and behavior.” which may explain the noted importance of meals such as breakfast to provide energy throughout a person’s normal daylight hours of primary activity.

In addition, future experiments should take into account the affect feeding mice exclusively during the daytime may have on final results. These nocturnal creatures’ behavioral patterns may change drastically based on when they are fed by their handlers, leading to sleep deprivation as mentioned above or the imbalance of their natural circadian rhythms. Those alterations in behavior can skew experiment results and lead to false data being accepted into the scientific record.

Dr. Takahashi believes his newly developed system can be the difference maker for future experiments. He stated, “this automated system, which can be scaled up for large and very long longevity studies, provides the means to address open questions about what mechanisms extend lifespan in mammals, and whether it is actually the calorie reduction or the time at which food is consumed that extends lifespan.” Whether scientists move towards adopting this system as the norm moving forward could determine the accuracy of experimental data in the years to come.

In the meantime, the UT Southwestern study could change the way we think about diets. Maintaining a proper routine to eat the right foods at the right time could make all the difference for someone hoping to shed weight. Cutting out the late night snacks may go a long way towards developing the body, and daily energy levels, one wants to see.

Other scientists working with Dr. Takahashi were  Dr. Carla Green, Professor, Distinguished Scholar in Neuroscience; Dr. Victoria A. Acosta-Rodríguez, Postdoctoral Researcher; Dr. Marleen H.M. de Groot, Research Specialist with HHMI; and Dr. Filipa Rijo-Ferreira, Associate with HHMI.



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