create the mind and what's the relationship between the mind and the brain. >> larry: they're different? >> well, i kind of think of the mind and the brain, the best way to communicate to people is, like music is caused by a bow going across the strings of a viol violin. it can be shaped and change the. but it's dependent on the violin and the bow to be created. >> larry: dr. amond, we're going to break this down by segments. we'll talk about overeating. everybody will know it's wrong to overeat and it's bad to be fat. why would you overeat? doesn't the brain tell you that's too much? >> not really. in fact, as your weight goes up, the actual physical size of your brain goes down. so your judgment -- >> larry: you get dumber. >> your reasoning goes down. the studies that we've done, so being healthy is critical to thinking right. but if you've had a brain injury, overeating goes up. if you've been eating badly for a long time, you become addicted