Tuesday, February 12, 2008

swanksalot: Circadian Riddems and Spare Tires

swanksalot: Circadian Riddems and Spare Tires

For some people, packing on unwanted pounds might have more to do with the functioning of their internal body clocks than with willpower.

Researchers from Northwestern University and Evanston Northwestern Healthcare have been studying how a faulty circadian clock, which regulates different parts of the body, including the mechanisms that control sleep and hunger, can damage the metabolism thus raising the risk for obesity and diabetes.
[From Researchers: Faulty body clock may lead to obesity, diabetes -- chicagotribune.com]


So far, 32 epidemiological studies have shown an association between inadequate sleep and higher body-mass index, a measure of overweight, said Dr. Eve Van Cauter, a professor of medicine at the University of Chicago. Van Cauter studies the effect of circadian rhythms on the endocrine system.

Van Cauter and her colleagues have published two studies examining the effects of short-term sleep restriction in young, healthy, lean adults. They found that individuals experienced different levels of hunger and satiety, depending on how much sleep they got.

"Leptin, an important hormone regulating appetite, is disturbed by sleep deprivation and no longer determines caloric need accurately," Van Cauter said.

In one study, sleep-deprived subjects were asked to rate their hunger for certain foods. Not only were they hungrier, they had a higher appetite for starchy, sweet and other high-carbohydrate foods.

"They did not have a need for food based on their energy expenditure, but they nevertheless felt more hunger," Van Cauter said.

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