The theory says that as you do additional exercise, you get diminishing returns in terms of the number of calories you burn. As your exercise level increases, you have to do ever more exercise to burn the same number of calories, because the body has various compensatory mechanisms designed to avoid weight loss.<p>The traditional model proposes a much simpler linear relationship: do an additional unit of exercise and you will burn X more calories, forever. He says that is incorrect and you actually get diminishing returns, where additional units of exercise burn ever fewer calories rather than just a constant.