Sex takes 6 minutes, 21 calories expended

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BIRMINGHAM, Ala., Feb. 1 (UPI) -- Sex takes, on average, 6 minutes and few calories are expended -- nothing close to the 100 to 300 calories often cited, U.S. researchers say.

An article published in the New England Journal of Medicine refuted several obesity myths including assertions such as sex uses about 100 to 300 calories.

"Everyone's trying to do something about obesity," David Allison of the University of Alabama at Birmingham told NBC News. "But if they are sending messages to the public that are based on erroneous understanding, arguably they may be wasting time and money and not pursuing the right things."

For example, the researchers said they found numerous citations that sex expends about 100 to 300 calories, but the only study the team found that came close to a scientific measurement of calories burned during sex was done in 1984 on 10 men -- a very small sample.

"A man in his early-to-mid-30s might expend approximately 21 calories during sexual intercourse. Of course, he would have spent roughly one-third that amount of energy just watching television, so the incremental benefit of one bout of sexual activity with respect to energy expended is plausibly on the order of 14 calories," the researchers wrote in the article.

The researchers also found there was no real evidence exists that eating breakfast helps people lose weight, children develop eating and exercise habits at an early age, or that eating more fruits and vegetables alone would somehow displace more calorie-laden food in the diet and help people lose weight.

What does work? Allison told NBC News drugs do to an extent, as does surgery to make the stomach smaller.

The paper was supported in part by the National Institutes of Health, but the researchers who worked on the article disclosed a long list of drug companies, soda companies, food companies, trade groups, members of the diet industry and other companies and organizations that paid them for consulting, speeches, board memberships; or supported them via grants or provided travel reimbursement.