Is Sex a Workout?

A CNN blog recently revisited the tantalizing myth that sex is a workout. It must be circulating pretty well right now on social media, as I have been asked by several people if this is true or not.

The article is referring to a 2013 publication from the New England Journal of Medicine entitled Myths, Presumptions, and Facts about Obesity, written by a prestigious group of experts.

Myth #7 states "A bout of sexual activity burns 100 to 300 kcal [calories] for each person involved."

The potential myth, which is highlighted by the CNN blog, is that "having sex one time burns about as many calories as walking a mile."

So, let's get it on.

Calories and 'METs'

Energy expenditure (calories "burned") during an activity is impacted by several factors, including:

1. The intensity (energy requirements) of the activity,
2. The time spent doing the activity, and
3. The body weight of the person doing the activity.

The metabolic equivalent or MET value of an activity allows us to figure out energy expended of any activity, for any person, for any length of time.

A 1 MET activity requires the same amount of energy as sitting quietly. A 2 MET activity requires 2 times the energy of sitting quietly, 3 METs requires 3 times the energy, and so on.

Very simply, you can take the body weight of a person (in kg) and multiply it by the MET value of the activity and get how many calories would be required and subsequently expended in doing that activity for one hour.

Mike weighs 200 lbs (91 kg), and wants to do a 3 MET activity (e.g. walking briskly at 2.5 mph).

91 kg x 3 METs = 273 calories, if he did the activity for one hour (60 min).

If he only walked for 30 minutes, then he would expend half, 136.5 calories.

Walking vs. Sex

Okay, so let's see if it is possible to expend the same amount of energy walking for an hour as having sex. Let's use Mike again (200 lbs).

The Compendium of Physical Activities, has three different levels of sexual activity.

Walking at 2.5 mph on a flat surface (3 METs) is the most commonly used walking estimation, as it meets minimum recommendations for moderate intensity activity (3-6 METs) = "a workout".

So, for Mike:

• Walking at 2.5 mph (3 METs) = 273 calories/hour
• Active, Vigorous Sex (2.8 METs) = 255 calories/hour

Close, but walking  wins out by 18 calories.

However, if Mike could bump up the intensity during his sexual activity to get to 3 METs (from 2.8), then he would expend same 273 calories per hour.

Actually, a more recent study found that free-living sexual activity resulted in 6.0 METs for young adult men, and 5.6 METs for women.

So, what if Mike was young and vibrant like the participants in this study?

• Walking at 2.5 mph (3 METs) = 273 calories/hour
• Sexual Activity (6 METs) = 546 calories/hour

He would expend DOUBLE the amount of calories expended in the hour! That would be equivalent to any other 6 MET activity, such as running at 4 mph. Sounds exhausting.

"What do you want to do, honey, go for an hour run or ...?"

6-Minute Sex

So, 60-minutes of sexual activity can be a workout, and can even expend as many calories or more than walking for an hour. In this case, the myth is BUSTED.

However, the CNN article and associated NEJM publication claim it is myth, because of estimates that the average sexual encounter only lasts around 6 minutes.

Clearly, 6 minutes of an activity is not going to match up to 60 minutes of another at a similar intensity. But, the study that concluded that sex lasted only 6 minutes was from 1984, and it was one study.

However, the more recent 2013 research study found the average sexual activity encounter between couples was 25 minutes.

The instructions, "In the present study, sexual activity was defined as the onset of foreplay, intercourse and at least one orgasm by either the man or woman, and ended at the couple’s discretion. During a one month period, couples were instructed to perform one sexual activity per week in their homes."

So, what if Mike, like some of these participants, got 30 minutes of sexual activity instead of 6 minutes?

• Walking at 2.5 mph (3 METs) = 273 calories/hour
• Sexual Activity (6 METs) = 546 calories/hour OR 273 calories/30-minutes

In this case, it is possible for Mike to have a sexual encounter that averages 6 METs and lasts for 30 minutes, which would be equivalent to him walking at 2.5 mph for one hour (273 calories).

The authors conclude, "The present study indicates that energy expenditure during sexual activity appears to be approximately 85 kcal or 3.6 kcal/min, and seems to be performed at a moderate intensity in young healthy men and women. These results suggest that sexual activity may potentially be considered, at times, as a significant exercise."

Conclusion

I said this one is CLARIFY, because you can 'foreplay' with the numbers to conclude that sex as a "workout" is either a MYTH or BUSTED. The key is determining the intensity of the sexual activity, how long it is performed, and how much the person weighs.

I normally recommend couples to count sexual activity towards their weekly physical activity, to help reach the 150 minutes per week.

I recommend that they enjoy both, walking and sex (not at the same time).

Caution!

Because sexual activity can get your heart pumping, the American Heart Association does suggest that concerned individuals should get a doctor's evaluation before resuming sexual activity.