Food and the Body Clock

If you had a holiday feast last night, you may be paying for it now. The science behind this is interesting, and may have important implications for efforts to fight the obesity epidemic. The holidays have a similar, though shorter-term, effect on diet and metabolism to working a graveyard shift; the body expects to eat at certain times, and when the expectation is not met, it can cause problems and be disruptive.

The body’s “food clock” is based in the circadian rhythm, which is the time keeping mechanism. The circadian turn is how you know when to get up in the morning and go to sleep at night—and feel hungry. However, this body clock doesn’t have a holiday setting. Holiday meals, being larger and earlier that what most people are used to everyday, confuse it.

Now scientists believe they have found the molecular basis for this phenomenon. A protein called PKCγ is used by the brain to regulate the timekeeping function and match the hunger cycle to paleolithic patterns of the availability of food. Large meals, or meals at odd times, disrupt the activity of this protein and throw off the cycle.

The researchers say they may be able to use what they’ve learned of PKCγ to help travelers fight the effects of jet lag. Jet lag occurs when the body’s internal timekeeping mechanism becomes uncoupled from the local time. By learning more about how the body clock is regulated, scientists can do more to help it adjust.

“Understanding the molecular mechanism of how eating at the ‘wrong’ time of the day desynchronizes the clocks in our body can facilitate the development of better treatments for disorders associated with night-eating syndrome, shift work and jet lag,” said University of California at San Francisco neurologist Louis Ptácek, an author of the study, in a statement.

So while your holiday blowout probably won’t wreak long-term havoc with your health, a habit of evening eating could. Night diners are more prone to obesity than people who start the day—and their meals—early in the morning. Learning how PKCγ shifts the body’s clock can help with finding ways to counter that effect.

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