As if you need another reason to do it.

Photo: Milkos / Getty Images

Before we even talk sex, a reminder: The days of obsessive calorie-counting and "burn it/earn it" workout mentalities (vom) are over. But if you're getting sweaty and out-of-breath in bed-and maybe even have some sore muscles the next day-it's only natural to wonder if that romp was as much of a workout as it feels like now. (After all, if Khloé Kardashian swears by sex as part of her fitness routine, it has to have some merit, right?)

Good news: You're not the only one wondering. "Believe it or not, I get asked this question a lot," says Jonathan Jordan, a certified trainer at Equinox and a fitness expert based in San Francisco. Researchers have even done full studies on the average calorie burn during sex. Here's what they found.

How Many Calories You Really Burn During Sex

One 2013 study published in the journal PLoS ONE found that, in young and healthy couples, men burned an average of 4.2 calories per minute and women burned an average of 3.1 calories per minute. During the average sex session (which in this study was 25 minutes), that translated to a total of 101 calories and 69 calories, respectively. (LOL good one, science.)

However, considering the real-life average bout of sexual activity only lasts six minutes, another study published in the New England Journal of Medicine hypothesizes that the actual calorie burn for the average person is much lower-closer to 15 or 20 calories.

Those second numbers are more in line with other estimates. For example, the 2011 Adult Compendium of Physical Activities (a resource that quantifies and standardizes the intensity of physical activities for research purposes) only ranks sexual activity as 1.3 METs (gentle) to 2.8 METs (vigorous). FYI: MET stands for metabolic equivalent, and it's used to estimate how many calories are burned during physical activity; 1 MET translates to roughly 1 kcal/kg/hr. Translation: A 140-pound woman weighs approximately 63.5 kg, so she'd burn about 63.5 calories per hour of a 1-MET activity (like lying on the couch and watching Netflix). That means she'd burn somewhere between 83 and 178 calories for an entire hour of sex. (Is this math turning you on yet??)

Before You Start Calculating...

"But everyone's caloric burn is different and it depends on your overall cardiovascular health, how high your heart rate gets, your resting energy requirements (your calorie burn at rest), etc." says Jordan. "It also depends on what kind of sex you're having." To judge how hard you're really working during sex, think of it like actual exercise: You're probably going to burn fewer calories if you're lying down vs. if you're in a more active position (hey, cowgirl!). Chiller foreplay (like kissing) will probably naturally be at a lower intensity and burn fewer calories than when you're going at it more intensely (ex: when you're both closer to orgasm).

"If your bedroom cardio looks like a few minutes of 'intense' work with a short break and then repeating, then guess what? You're basically doing HIIT," he says. Or, at least, you might be doing HIIPA, high-intensity incidental physical activity. Yes, that's a new thing: Fitness professionals and researchers are starting to see more value in non-exercise activities that get your heart pumping, and an editorial published in the British Journal of Sports Medicine argues that any activity that gets you out of breath can count as a sort of mini HIIT workout. (And that could most definitely include sex.)

But-for your sake and your partner's-please don't go overboard trying to calculate your calorie burn with a calculator or wearable. "It's annoying enough when people become obsessed with tracking and hold up training sessions or classes because they can't possibly exercise without tracking," says Jordan. "I love tracking my fitness too, but I shudder at the thought of using it during sex...The stress relief and relaxation benefits of sex could be a great thing for your body; they could lower stress hormones and make your body healthier, happier, and more able to burn fat." But if you're worried too much about your Fitbit or about burning calories, you likely won't get all those great benefits or enjoy yourself. (A much better goal? Multiple orgasms.)

So while sex isn't exactly equivalent to a spin class (unless you do it like Ariana Grande at the 2016 VMAs??) you can sure as hell enjoy it knowing you're earning all these amazing health benefits of sex regardless of how many calories you're burning. (And, FWIW, hitting the gym pre-hookup actually makes for great foreplay.)