How many kilojoules do you burn during sex?

By Amy Rushlow

Ever wonder what kind of workout you get between the sheets? Thanks to new research from the University of Montreal, we have the precise answer: men burn 418 kilojoules (about 1000 calories) in the average sex session, while women expend just 289. (Yes, that is 69 calories.)

The typical romp lasts 25 minutes from the start of foreplay to the end, but that’s just an average—the times varied widely in the study, and ranged between 10 and 57 minutes. The longer the session, the more calories burned.

At this point you’re probably thinking, “How the heck did they find this out?” And it's true that previous studies on the topic generally required sex in a lab with electrodes, cables, cuffs, and a mask worn over the mouth—which, as you can imagine, limited pleasure for all but the most sexually adventurous subjects. But new technology allows the same information to be calculated from an unassuming armband that can be worn at home, leading to more realistic data.

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In addition to having their lovemaking monitored by the sex equivalent of a Fitbit, 21 couples also ran on a treadmill for 30 minutes to compare "sexercise" to actual exercise. For men, running at a moderate pace burned more than twice as many kilojoules per minute, 1155 total. When asked which was more pleasurable—doing the deed or pounding the treadmill—100 per cent of men said sex. (There was no write-in option for “You really had to ask?”)

“The level of intensity that is exerted from sexual activity could be higher than that of walking at [5kms per hour] but less than that of jogging at [8kms per hour],” the researchers write in the study, which was published by the journal PLOS ONE. “Taken together, these results suggest that sexual activity may potentially be considered, at times, as a significant exercise.”

To calculate how many calories you burn the next time you have sex, multiply the time in minutes by 4.2 (for men) or 3.1 (for women).

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*Portions of this story originally appeared on Prevention.com.