I don't usually pay for it ;0)

It depends how much energy you use. And how long the sex lasts. Bro, if you just lie there, looking at porn, eating chocolate, and jerking off, you will gain weight.

In minus!

Depends how vigorous you are!

About 100 calories are burned every 20 minutes, or so I've read.

1) Here a comparison of the number of calories burned by different activities. I set for each a value of 20 minutes and assumed a weight of 150 pounds. "Activity Calories burned Sitting / resting 24 Reading 24 Sex - foreplay 33 Driving 48 Cooking 60 Bicycling - leisure 90 Sex - intercourse 96 Walking 4 mph 117 Swimming - moderate 138 Jogging 159 Walking - up stairs 183" "Find out how many calories you burn doing your favorite activities or how long you should do an activity to lose weight. Enter your weight, then enter the number of minutes you do each different activity, click on calculate at the bottom of the form for your personal report. Knowing the number of calories you burn in conjuction with a sensible diet can help you lose or gain weight." Source and further information: http://www.healthstatus.com/calculate/cbc Further information: - "calories Burned During Sex": http://www.c4vct.com/kym/humor/csex.htm 2) "A pound of fat represents approximately 3500 calories of stored energy. In order to lose a pound of fat, you have to use 3500 more calories than you consume. It's best not to do this over the course of a day; you'd probably hurt yourself, and your body (knowing it, the uncooperative creature) would probably have some extreme reaction which did not involve you losing any actual weight. It's better to spread this out over a week, so that you aim to exceed your caloric requirements by 3500 to 7000 calories per week, resulting in weight loss of one to two pounds per week. It's not healthy to try to lose more than two pounds in a week, and if you do attempt to do so you're unlikely to be successful. Not sure how much weight you need to lose? Check a BMI calculator and a body fat calculator. Make it your goal to hit the right BMI and body fat percentage for your height. Let's say you want to lose two pounds per week. To do so, you need to figure out how many calories a person of your age, sex, and weight usually needs in a day (see Eat Less), subtract 500 from that amount, and follow a diet that provides you with that many calories. For example, if you would ordinarily need 3000 calories in a day, you would follow a 2500 calorie per day diet. Then you figure out how much exercise a person of your weight would need to do to burn 500 calories per day (see Exercise), and you get off your lazy ass and do it. The result is simple. 500 fewer calories consumed plus (minus, actually, but we don't want to confuse you) 500 more calories expended equals a 1000 calorie per day deficit, which, over the course of a week adds up to 7000 calories, or two pounds. Your mileage may vary, but there's no getting around it. If your body is consuming fewer calories than it's expending, something's got to go (see God, "The First Law of Thermodynamics"). That's how it works. Now you just have to learn how to eat less (see Eat Less) and exercise (see Exercise) and you will lose yourself some weight." Source and further information: http://www.soyouwanna.com/site/syws/loseweight/loseweight.html