[konstruktor]

Assuming you are talking about 500kcal per exercise session: This results a total of 130000kcal per year, or the nutritional value of more than 16kg of fat. So how is your example an argument against outrunning your fork? If you enjoy both eating and exercise, this may as well be the way of least resistance.

[skunkworks]

Because your body will signal that it needs more calories, and then you'll eat more calories.