Our bodies contain clocks that regulate everything from our sleep to weight. These clocks consist of a set of genes that underlie the “timing” of the clock. They also control our metabolism, or the process by which our bodies convert food into energy. Metabolic disorders are serious illnesses that can take many forms. Thus, understanding how they work and developing interventions are of the utmost importance.
Lots of metabolic research is done with mice. When mice are provided free access to unhealthy food, they develop metabolic issues. Researchers have observed that these mice also show disrupted cycling of their core clock genes. But when the same mice are given access to the unhealthy food during only a subset of the day, many of the negative metabolic and clock gene consequences are ameliorated. This led to the hypothesis that clock gene cycles could be a primary mediator of a healthy metabolism. This is really important for people who do shift work, or those who are exposed to particularly high light levels at night, both of which disrupt normal human circadian rhythms. The video below explains more background information on this idea.
Researchers at the Salk Institute recently published their investigation of how to prevent obesity in mice with dysfunctional clocks. Mice in their experiment were given an unhealthy diet, with food available either throughout the day or just in a nine-to-ten-hour-long window. The overall caloric intakes of the two groups of mice were kept the same. The researchers then measured several markers of metabolism function. They found that the restricted feeding time kept mice metabolically healthy and lean, even when they lacked a regular circadian rhythm. So, rather than regulating metabolism the clock's main function may be to control the behavioral rhythms of feeding and fasting.
This is exciting in that it lays the foundation for human studies regarding how timed eating can override the consequences of clock disturbances. Regardless, at this point I don’t think it would hurt to put down that midnight scoop of ice cream (or at least have it earlier in the day!)