Q. When you eat something you really like and that tastes good, why do you keep eating it? The second mouthful (or so) certainly doesn’t taste any better (or different) than the first one.
A. Susan B. Roberts, PhD, director of Tufts' HNRCA Energy Metabolism Laboratory and author of The "I" Diet <theidiet.com>, replies: "There is no definitive answer yet, but this seems to involve several centers in our brain. The orbitofrontal cortex (front of the brain) processes taste information, recognizes tastes and also seems to be involved in something called sensory specific satiety, which is a technical term for taste saturation. We need to eat a certain amount of a food before those neurons are satisfied for taste. So, one bite doesn’t do it.
"In addition, our reward center in the midbrain gets activated for the prospect of food and available food of a kind we like, so until our sensory-specific satiety mechanism tells us the portion size is sufficient, addictive chemicals are released, such as dopamine, to keep us eating."