“And therein lies another key difference between walking today and in ancient times. If I walk ten thousand extra steps to place my body in negative energy balance, it is literally a piece of cake for me to wipe out the extra cost of such a walk. The ease of refueling with a donut or a Gatorade or just by sitting at my desk for the rest of the day helps explain the counterintuitive result we just saw from the DREW study in which the women who exercised the most lost less weight than predicted: they ate more.36 Happily, more than a dozen studies on the effects of exercise, food intake, and non-exercise physical activity on weight loss found that modest doses of prescribed exercise rarely cause people to spend the rest of the day as couch potatoes erasing the benefits of their exertions.37 However, several experiments that required large doses of exercise (one involved training for a half marathon) did cause exercisers to eat more.38 When the body regulates energy balance like a thermostat, it apparently does so more through diet than through physical activity.”