I was bored!

The naked truth
A good session in the sack burns approximately 150 calories for every 30 minutes you indulge – better than a yoga class (at approximately 115 calories) and the equivalent to a brisk half-hour walk. And it's not just the nitty-gritty of sex itself – snogging alone burns between 60-90 calories in the same timeframe (depending on just how 'French' your kissing gets), while a vigorous half hour of oral sex can add another 120 calories to your sexercise total. Indeed, according to the Kinsey Institute the average human loses nearly 5lbs a year through having sex (while for those of you bemoaning the fact that you ain't getting any, an energetic masturbation session can reap similar rewards).