Chicken or Egg?

In an interesting follow-up to the study that showed that children who don't get enough sleep have higher obesity rates, comes this study:

Eating just a few meals loaded with fat -- think holiday food -- could be enough to throw off the body's internal clock, starting a vicious cycle that could lead to obesity and diabetes, U.S. researchers said on Tuesday.

They found mice fed high-fat foods showed marked changes in their diet and sleep patterns, sleeping longer and eating when they should be sleeping.

"The effect can be seen quite rapidly -- within a matter of days," said Dr. Joe Bass of Northwestern University and Evanston Northwestern Healthcare in Illinois, whose study was published in the journal Cell Metabolism.

He said the study suggests overeating alters a core mechanism of the body clock, disrupting the timing of internal signals like appetite control.

"What we saw is that the ticking of the clock slowed down," Bass said in a telephone interview.

Known as the circadian clock, this internal time keeper manages the body's daily rhythms, regulating when to sleep, wake, eat and many other functions of the body.

Prior studies led by Bass found that a faulty body clock can raise the risk of obesity and diabetes. Bass' latest study shows that overeating can trigger this process.

So a lack of sleep can cause obesity - whether from a messed up body clock, or from just not getting yourself to sleep early enough. But the trigger to the faulty body clock could be the overeating. And to further confuse the matter, mice who overate were found not only to sleep poorly - but eat more and at inappropriate times:

"If you give a mouse a high-fat diet, they will eat excessive amounts," Bass said. "It is the same thing as human eating at McDonald's or eating too much at a Thanksgiving dinner."

So the question is, where does this vicious cycle of high fat diet/weight gain/sleep disruption/high fat diet/weight gain/sleep disruption start?