Turns out that junk food elicits addictive behavior in rats similar to the behaviors of rats addicted to heroin. And in humans, addictive behavior similar to addictive behaviors related to other drugs such as cigarettes, alcohol and vicodin.

Sure enough, the studies showed that junk food affected the brain's natural reward system, releasing feel-good chemicals after noshing on chips, cheesecake and candy. The consumers ate more calories and fat from the junk food (after fasting for 6 hours) than non-addicted munchers consumed from regular food, after fasting for the same length of time.

These same pleasure centers in the brain are the same ones stimulated by drug addiction, lighting up after consumption. And, as in drug addiction, more and more junk food was needed over time to get the same level of "high", a hallmark of addiction. There's no such thing as a little bit. You can't eat just one.

For those of us fighting the addiction to junk food, the sad news is that the reward pathway deficits persist over time. Backsliding is common and it's much harder to do the second time around. The salt-sweet-sugar junk food addict would rather starve than eat salad and is strongly motivated to seek out his food of choice (gimme ice cream!).

Alas. Cold turkey is the only way to quit.