We are all well aware that eating diets high in fat and sugar will lead to obesity. Somehow, the solution should be just as easy: stop eating fat and sugar. Yet, for obese people, fat and sugar are craved like heroin or methamphetamine: Why? The answer is that these diets actually change how the brain functions.
Day after day, year after year, the constant bathing of the brain and body in fats and sugar slowly changes how the DNA in the cells of our brain's feeding center behaves. Due these gradual modifications in gene function, our brain circuitry changes; ultimately, it rewires itself to crave these foods. The pattern of our eating changes so that we eventually eat more every day in order to feed this ever-more-powerful new software program that is evolving inside our brain.
Initially, scientists assumed that obese people were simply addicted to food in the same manner that someone becomes addicted to heroin, i.e. food produces happy pleasant feels, and therefore eating lots of food would produce extremely pleasant feelings. Not so. A few years ago scientists discovered just the opposite was true; the brain's reward center decreased its response to eating tasty foods. This induces people (and animals in experimental studies as well) to consume ever greater quantities of fat and sugar in order to mitigate the diminished rewards that were once experienced by consuming only one scoop of ice cream or a small donut.