17 November 2004


Sleeping can help you lose weight? I didn't believe it the first time I saw it, and when I read it, I still can't believe it.

The new finding is based on data collected from the National Health and Nutrition Examination Survey I (NHANES I), which involved more than 9,000 people.

Here are the findings:

People who reported getting less than seven hours of sleep a night were more likely to be obese on initial evaluation. The study also showed that they were also more likely to develop obesity during follow-up.

Participants who slept five hours per night were 73 percent more likely to become obese than those getting seven to nine nightly hours of sleep, say Columbia University professor of medicine Steven Heymsfield, and James Gangwisch, PhD.

Even one hour of sleep can make a difference.

People getting six hours of sleep per night were 27 percent more likely to become obese than those getting seven to nine hours.

The lightest sleepers --- those with only two to four hours of sleep per night --- were 67 percent more likely to become obese than people who slept for seven to nine hours.

[WebMD, Nov 16 2004]

The researchers admitted that "more work is needed to explain the sleep-obesity relationship."

The seeming logic is that if you sleep less, you have more time to eat.

Some studies have shown that lack of sleep can affect insulin sensitivity and levels of two appetite-related hormones --- leptin and ghrelin -- which, in turn, can affect weight gain.

Leptin is a hormone associated with appetite control while ghrelin is the hormone identified as an appetite stimulant. In clinical studies it has been shown that, leptin levels fall and ghrelin levels rise.

This may be one way of looking at the sleep-obesity relationship. In my opinion, a sleeping time limit should be set. Sleeping 7-8 hours every night should be the limit.

Sleep lasting less than 7-8 hours per night might indeed bring on weight gain as reported by the study. But sleeping more than 7-8 hours per night might also be associated with weight gain. Less movement also means less calories are burned. Also, sleeping more than 8 hours can produce a "starvation phase" which might make you eat more than what is expected upon waking up.

I still believe that physical activity remains one of the best ways to combat obesity.

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