According to the Obesity Policy Report (by way of ConsumerFreedom.com), the lead author of the unpublished study that the New York Post cites in its article equating hamburgers and heroin says his work was taken out of context:
Addiction is kind of a vague term, and we obviously can't say that we've proven that you can become addicted to food. All we found is that there are similar findings between this high-fat diet we gave the rats and what you see after similar schedules of morphine in rats….
We have no idea what it does to their behavior necessarily. We're exploring that in the future. All we have right now are the parallel changes in the biochemistry.
Do we really need to look at rat brains or rat behavior to know that people often have trouble resisting tasty foods? That they crave them and feel worse without them? That they try to cut back in an effort to lose weight but often "relapse" because of the pleasure and comfort the food provides? Few facets of life in 21st century America are more familiar than the conflict between the enjoyment of food and the desire to be thin. Burgers and fries are addictive in the sense that any source of pleasure (or relief) can be the focus of a hard-to-break habit. The question is, so what?