If you're looking to shed a few extra pounds without leaving the bedroom, you better clear out your schedule.
We tend to overestimate the utility of sex as a weight loss tool.
That's the conclusion of a paper published in the New England Journal of Medicine by researchers from the University of Alabama at Birmingham, who investigated the correlation between sexual activity and weight loss.
The authors specifically investigated and debunked the myth that a romp in the hay burns 100 to 300 calories per partner. (What we call calories in food are technically called kilocalories in scientific research on diet and exercise, according to the United States Department of Agriculture.)
"Given that the average bout of sexual activity lasts about six minutes, a man in his early to mid-30s might expend approximately 21 [kilocalories] during sexual intercourse," the research found. (That six-minute figure matches the findings of studies reported by Esquire [five to seven minutes] and Medical Daily [5.4 minutes].)
Naturally, longer sessions of hanky-panky burn more calories.
A 154-pound man would burn about 210 kilocalories during an hour of sex, according to the paper.
The intensity of physical activity is measured in metabolic equivalents, or METs, according to the Harvard T.H. Chan School of Public Health. Walking slowly rates 2 METs. Recreational badminton rates 4.5 METs. Jogging 6 mph rates 10 METs.
The University of Alabama researchers assigned sex an intensity of 3 METs. This falls in line with the approximation offered in a 2003 article in the American Journal of Geriatric Cardiology, which found that more energy was burned during orgasm, while foreplay involved a lower energy expenditure.
Getting back to that 154-pound man ...
To arrive at the estimate of 210 kilocalories for an hour of sex, the University of Alabama researchers multiplied a person's weight in kilograms (154 pounds is roughly 70 kilograms) by the MET (3).
But, as the research pointed out, most times we "do it," it doesn't take quite that long.
As an hour has 10 six-minute intervals, the average shag burns 1/10th of the hour's worth of kilocalories, or 21.
Even an hour of intercourse doesn't compare to running a marathon.
An hour of sex expends energy comparable to that spent in an hour-long, two-and-a-half mile walk, the research found.
So if you're looking to burn calories, shacking up probably isn't the most efficient way to do it.
Even though sex might not lead to short-term weight loss, the "love hormone" oxytocin — which both men and women experience during orgasms — has been linked to a long-term decrease in food cravings.
People with high oxytocin levels were less likely to binge eat, according to a 10-year study by researchers at Canada’s York University and the Center for Addiction and Mental Health found, Maxim reported.