Does Sex Burn Calories? Not Many [Study]

Sex burns calories. It’s kind of an axiomatic truth in our culture. But how true is it? Not very, according to a recent study.

Researchers looking into the science behind assumed truths regarding obesity (skipping breakfast is bad, so is snacking, gym class makes a difference) found that some of these long-held beliefs might not have a lot of truth behind them.

Their report in Thursday’s New England Journal of Medicine says that these poor assumptions are distracting our culture from working out real solutions to the problem of obesity.

“The evidence is what matters,” said the lead author, David Allison, a biostatistician at the University of Alabama at Birmingham. According to Allison, assumptions like “sex burns calories” don’t have very much evidence to back them up.

The AP reports that independent researchers fact-checking the report concede that the authors raise valid points, but question their ties to food, beverage, and weight-loss product makers. The disclosures in the report take up half a page of fine print.

“It raises questions about what the purpose of this paper is” said Marion Nestle, a New York University professor of nutrition and food studies.

“The big issues in weight loss are how you change the food environment in order for people to make healthy choices,” like limiting soda sizes and marketing junk food to kids. Some of the “myths” the research cites are “straw men” issues, she said.

Still, the study arrives to some interesting conclusions regarding weight loss myths that many agree with. “I agree with most of the points” except the conclusions that meal replacement and diet drugs work to battle obesity, said Dr. David Ludwig, who does obesity research with Boston Children’s Hospital (and has no industry ties). Ludwig says “there’s much more evidence of failure than success,” for such replacements.

So conclusions and ramifications aside, what did the study manage to “bust” as popular weight loss myths?

Sex burns calories? Not as many as you might hope. One study done in 1984 only measured the man’s experience, and sex lasted six minutes on average, burning … 21 calories. A far cry from the 100 to 300 calorie claim.

Gym classes for children usually aren’t long or rigorous enough to make a real difference.

Losing a lot of weight quickly is worse than losing it slowly over time.

Snacking does not lead to weight gain, though that might depend on what you choose to snack on.

Whether or not you miss breakfast has no effect on weight.

What do you think? Are you surprised that there isn’t much evidence behind some of our long-held assumptions about weight loss?