Instinct vs. Willpower

Recently I've began reading "The end of overeating" by David A. Kessler. The book took an approach at explaining the phenomenon of human obesity that suggests that we are not rationally in control of what we eat in some instances. It turns out that an area of the brain known as the "reward system" has receptors that are stimulated specifically by three main tastes: Salt, Sweet, and Fat. The brain is essentially addicted to these flavors and it has been proven that the severity with which we crave them is almost as bad as that of a person with a cocaine addiction. Based on this logic, it becomes increasingly less of your choice every time you decide that you want to pick up some McDonalds because you're simply enforcing an addiction that chances are you aren't even aware of.