While the physics of weight loss certainly supports diet over exercise, let's also consider the overall effect of our sedative culture. I believe it contributes greatly to the modern afflictions of anxiety and depression. That our bodies crave more physical activity, as the legacy movement is in our biology, only recently shut out in the last couple hundred years (or less).

When you think about how much someone eats, it helps to think about why. The exercise could help on more than one front.