 [ Symptoms ] how many calories does sex burn [ Disease ] thirty minutes of sex burns 85 calories or more it may not sound like much but it adds up 42 half hour sessions will burn 3 570 calories more than enough to lose a pound doubling up you could drop that pound in 21 hour long sessions sex is a great mode of exercise  says patti britton phd a los angeles sexologist and president of the american association of sexuality educators and therapists it takes work from both a physical and psychological perspective to do it well she says