You open a bag of chips and plan on only eating a few from the bag. Before you know it, the entire bag is gone. Perhaps you decide to eat a scoop of ice cream, but somehow, you ended up finishing the entire tub instead. Everyone has encountered situations like these before. However, there are some people who have a lack of self-control, and it leads to them compulsively overeating, which poses a threat on their health and put them at a high risk for obesity.
neural pathways in the brain with regards to these types of reward and
motivational behaviors. Foods that
are particularly high in fat and sugar are highly associated activating these
systems in the brain. Obesity is
becoming a growing problem in the United States recently; in the “past three
decades the average prevalence of obesity in the US adult population has risen
from below 20% to 35.7%” (Stice et al. 2013, 2). The fight against obesity in the United States is not a
simple one. The problem of obesity
can be looked at similar to that of drug addiction. Telling a drug addict to “just say no” to drugs is not very
effective. Likewise, telling
people to simply eat less or to “just say no” to foods high in fat and sugar is
not that easy either. People tend
to generally place the blame on the individual for overeating, but that may not
simply be the case. There are
neurochemicals reward pathways in the brain that are strong enough to override
the normal willpower in controlling people’s hunger, resulting people eating
more than they want and placing them at a higher risk for obesity. Recent research has shown that there
are many parallels between the behaviors of overeating and drug use in the brain. Analyzing obesity with this perspective
and by showing how compulsive overeating can have the same effects of drug use on
the neural pathways in the brain can help researchers to further understand the
underlying pathology of obesity as not just a metabolic disorder, but as a
brain disorder as well.
The main pathway that is involved in the reinforcing and addictive behaviors in drug abuse is the mesolimbic dopaminergic pathway. Research has shown that the signals that inform the metabolic and nutritional status act on the same pathway of the brain as well, as these signals travel to the mesolimbic dopamine neurons that has projections to the ventral tegmental area (VTA) to the nucleus accumbens. The VTA, nucleus accumbens, and other striatal regions of the brain are activated when either a drug or a certain palatable food activates the reward pathway. Overlapping signals of the same regions of the brain in both drug use and particular foods show that both behaviors are engaged in the same reward pathway in the brain.
Food and drug intake are also similar in their effects on dopamine signaling and can affect the neural plasticity of the reward pathway. Consumption of foods high in fat and sugar enhances the release of dopamine in the striatum, resulting in the increased feeling of pleasantness after eating a meal high in fats and sugar. Over time, due to the increased levels of dopamine in the brain, there is an alteration in the neural pathway, resulting in the decrease of D2 receptor binding and availability in the striatum and other brain regions involved in the pathway. By altering the sensitivity of these regions, the down regulation of receptors cause an increase in the behavior, such as overeating or increased drug intake, in order to release more dopamine to maintain or increase the same pleasurable effect due to the behavior. This tolerance to a drug or food has detrimental effects on a person as it results in a person consuming more of the food or drug, leading to dire consequences in their health.
It can be said that foods highly processed in fat and sugar is biologically addictive, as these types of foods can overstimulate this reward pathway. A study has shown that even though the rats were trained to fear the shock, the rats would disregard the warning signal before the shock and continue to eat the high-calorie foods high in fat and sugars. Their uncontrollable desire to devour these types of food regardless of their trained fear of the shock shows how powerful the motivational reward pathway in the brain can be. Because this behavior physically alters and rewires the neurochemicals pathways in the brain, it becomes difficult for people to break the habit of overeating.
There are slight differences, of course, between overeating and addicted drug use. Even though both food and drugs serve as strong reinforcing attributes to this neural reward pathway, food is considered necessary for survival while drugs are not. Overall, similar neural pathways are being used in the brain from addicted drug use and uncontrollable eating and how these behaviors are physically altering and rewiring the reward pathways in the brain. This lack of self-control can lead to many people in becoming obese, which is why it is currently becoming a growing problem, as obesity is shown to be more than just the problem of the individual at the surface. Seeing parallels between the two behaviors of overeating and addicted drug use can provide valuable insight and a new perspective into further research toward designing new treatment approaches for obesity.
Hyman, Mark. "Food Addiction: Could It Explain Why 70 Percent of America Is Fat? - Dr. Mark Hyman." Dr. Mark Hyman. Np.p., 18 Oct. 2014, Web. 03 Mar. 2015.<http://drhyman.com/blog/2011/02/04/food-addiction-could-it-explain-why-70-percent-of-america-is-fat/#close>
Kenny, Paul J. "Is Obesity and Addiction?" Scientific American. N.p., 20 Aug. 2013. Web. 10 Mar. 2015. <http://www.scientificamerican.com/article/is-obesity-an-addiction/?page=1>.
Stice, Eric, Dianne P. Figlewicz, Blake A. Gosnell, Allen S. Leine, and Wayne E. Pratt. “The Contribution of Brain Reward Circuits to the Obesity Epidemic.” Neuroscience Behavior Review 37 (2013): 1-24. Web.