In a world where the average person makes over two hundred food decisions each day, it is hard not to question the ultimate reason for why we eat foods, particularly unhealthy foods, that are making our country obese. In more recent years, scientists have started to look beyond the influence of our immediate environment and have begun to explore the impact of biology on our eating behaviors. The question is, at what point, if any, does our biology overtake our free will? Do we even have free will over our eating behaviors, or does our biological foundation solely dictate what, how, and when we eat?

Scientists at the University of California at Irvine, and the Italian Institute in Genoa sought to find out if humans are driven to eat certain types of food. In this study published in the Proceedings of National Academy of Sciences, rats were fed a liquid diet high in fat, sugar or protein and observed for possible effects.  When rats were fed a high fat diet, their intestines released a regulator chemical called endocannabinoids, similar to the chemical released with use of Marijuana. This chemical is responsible for controlling of appetite; when released after eating a fatty meal, it positively stimulates the brain to want more foods with fat. Consuming high sugar or high protein diets did not cause the release of endocannabinoids.

Author of the study and director of drug discovery and development at U.C. Irvine Dr. Daniele Piomelli explains, “we have this evolutionary drive to recognize fat, and when we have access to it, to consume as much as we possibly can.” Accordingly, since fat is required by our cells for normal functioning, our brain tells us that we not only like fat, but also we need it.

But, are all individuals alike in their response to fatty foods? As seen in Dr. Carnell’s study at Columbia University on comparing brain activity in obese women versus brain activity normal-weight women when presented with food, the answer is No. The study revealed an amplified response to food images in the brains of obese women compared to their normal-weight counterparts. Carnell describes that in the obese women studied, “reward centers were activated just by saying the words ‘chocolate brownie.”

Further research into the relationship between biological reward systems and eating behavior will give insight to the public as to the why some find themselves constantly reaching for that bag of chips, possible behavioral adjustment that’s can be made in cases of high brain response to food, and fuel for drug developers to target reward systems to prevent overeating habits.

Sources: Proceedings of the National Academy of Science. July 5, 2011; New York Times