There is some question about the role particular diets have on our moods. The bigger question seems to what role emotions have on how and what we eat.
There are chemicals in our central nervous system that trigger a variety of emotions like joy, elation, worry, depression and so on. There are certain feel-good secretions which, when coursing through our system, make the world seem a rosy place. When there are less of these, they immediately make us feel low and the direct consequence is a longing for food.
The food our system desires at such times is rather unhealthy. The body craves starchy, fatty food, full of sugar or salt. Such negative feelings therefore control your diet and derail it by attempting to attain the emotional high you would get otherwise from the chemicals in the brain.
Richard Gould, author of “Shrink Yourself” talks about being able to distinguish between hunger and emotional needs:
You crave specific foods - generally not carrot sticks or steamed broccoli.
Cravings for specific, usually unhealthy foods is a sign of emotional eating. Often people like the rush they get from satisfying their cravings. That rush is fulfilling emotional hunger.
Your hunger feels urgent.
You need a particular food right away and you're willing to walk out of your way, or get in your car late at night, or raid your kid's Halloween candy to get it. Physical hunger, unless you haven't eaten for a very long time, is usually pretty patient. It will wait for food. Emotional hunger demands to be satisfied immediately.
