Same thing happens without the supershoes... Start running to get fit, expending X calories per mile. If you lose weight due to all the running/exercise, well

Same thing happens without the supershoes... Start running to get fit, expending X calories per mile. If you lose weight due to all the running/exercise, well, then, you've made it easier for your body to cover the same distance since you weigh less now. But your weight loss will decrease if you keep your running distance constant since your lighter body requires fewer calories to cover the same distance.