There are 3500 calories in a pound of fat. For every 3500 calories you burn (that you do not replace with food!) you will lose one pound of fat. Sexual intercourse burns approximately 150 calories per half hour. Here?s how that stacks up against some other activities that may be part of your fitness regime: yoga 114 calories per half hour, dancing – rock 129, walking – 3mph 153, weight training 153, canoeing – 2mph 153, volleyball 174.

Don’t have enough fingers to count that high? Use this Special Calculator to help you figure out how many pounds a year you’re burning between the sheets and in the airplane bathroom.