“What else you do alongside kissing makes a big difference,” holistic nutritionist Rachel Fiske, N.C., CPT-NASM, tells mbg. “If you’re getting hot and heavy, using your hands and moving your body a lot, the caloric burn is dramatically increased. Just like with other forms of exercise, standing and involving multiple muscle groups boosts calorie burn.” That said, according to a review4 published in the New England Journal of Medicine, the exact number of calories burned during sex fluctuates depending on the intensity level of the activity, the individual’s body weight, and how long the sex lasts. But your mouth isn’t necessarily the only muscle group getting a workout when you’re smooching, he notes. A whopping 112 postural muscles—the core stability muscles found in your pelvis, abdomen, and back—can also come into play depending on your position throughout the kiss (are you sitting, standing, lying down?), how physically intense the kiss is, and how much you’re moving during it. In other words, the hotter the kiss, the more calories you’ll burn. Personal trainer and nutritionist Jamie Hickey tells mbg your body burns calories through a metabolic process in which food and drink are converted into energy sources by combining calories with oxygen. From there, the energy is released into your body for it to be utilized: to allow your heart to beat, your lungs to compress and decompress, and to perform every other function it needs to survive, Hickey explains. But in terms of kissing, your body burns calories through oxygen deprivation. “Oxygen consumption is very important to burning calories, [and] if you’re breathing heavy, your heart needs to beat faster to make sure it’s spreading fresh oxygenated blood to your muscles, and brain,” says Hickey. “This causes your body to burn calories in order to match the energy levels your body is requiring.”
