Why Am I So Hungry?

In the web article, “Wired for Hunger: The Brain and Obesity,” Marcelo O. Dietrich and Tamas L. Horvath describe the epidemic of obesity. I learned that both evolutionary and genetic factors play a major role in our intake of food. Our human ancestors lived in a world where food was not always available. Whatever they could find was eaten and stored for survival. Food was also widely dispersed and early humans had to migrate very often to obtain it, which required high amounts of physical activity. On the contrary, people today can easily obtain food and most do not incorporate much physical activity into their lives. This is what has lead so many to obesity today. Early humans were constantly searching for food, consuming food, and storing food so that they could survive. Evolution has shaped us to have these same needs, although our food availability has drastically changed. Because we eat more and exercise less, we consume more calories than we burn off. This is known as a positive energy balance, the source of obesity. The brain plays a major role in sustaining energy balance. The arcuate nucleus (ARC), located in the hypothalamus, is one area that helps regulate this balance. The melanocortin, system located inside the ARC, is the main system that regulates the food we consume. This system has two opposing neuron groups that act against each other. One manufactures melanocyte-stimulating hormones (MSH) that curb our appetite. The other produces molecules that stimulate our appetite and inhibit MSH hormones, and they include the molecules neuropeptide Y (NPY) and agouti-related protein (AgRP). These molecules battle against the MSH hormones to attach to the same site on the melanocortin receptors in our brain cells. Therefore, the interaction between our appetite stimulating and appetite inhibiting neurons regulates food intake. Our urge to eat comes from the inhibition of MSH hormones, and unfortunately, the default wiring of our brains tells us to keep eating even though we don’t need to. After reading the journal article “Consuming Passions” by Karen Wright, I learned that both the stomach and the brain cause hunger. This double whammy can be especially tough for those trying to lose weight. Hunger in the brain is more about the pleasure aspect of eating, so it is harder to get rid of. It controls the eating binges we sometimes have and the cravings we have for certain foods. We are rewarded while eating by sensations and impulses that leave us wanting more. Studies have found that even looking at food or smelling food releases dopamine in our brains which causes feelings of enjoyment and pleasure. These rises in dopamine levels have