"We have demonstrated that mice eating at the 'wrong' time of day have increased weight gain compared to mice eating at the 'right' time of day," Arble said.
Similar to that of the mouse, humans' internal clock governs daily cycles of feeding, activity and sleep. Recent studies have shown that the body's internal clock also regulates energy use, which suggests that the timing of meals may make a difference in balancing caloric intake and energy expenditure, the researchers say.
But it is also important to not lose sight of the importance of total caloric intake, Arble said.
"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. However, for the individual who is not consuming excess calories and is still gaining weight, this experiment in mice suggests a new factor to examine -- the timing of feeding."
Dr. Luigi F. Meneghini, an associate professor of clinical medicine at the Diabetes Research Institute of the University of Miami Miller School of Medicine, believes the level of activity of the mice may be one reason for the difference in weight gain.
Meneghini noted that the mice fed at the "wrong time" exercised less than the mice fed during the normal wakeful hours. "Maybe something happens with circadian rhythms or hormones that make it less likely that they will engage in physical activity," he said.
"Based on this small study, if one were to say is it caloric intake or physical activity that led to the difference in weight gain, one would surmise it was more likely physical activity," he said.
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