AP Biology class blog for discussing current research in Biology

Blame your Brain for Gluttony


Everyone knows that chocolate is delicious, but usually, humans don’t eat 5 percent of their weight in M&Ms.

Source: flickr
Photo taken by silkegb

According to a recent study, researchers at the University of Michigan have recently discovered that neostriatum, a part of the brain, is directly linked to the desire to overeat. After a series of experiments and tests, the scientists concluded that a rise of chemical compounds in the neostriatum causes the human or rat to consume food without restraint.

During the first study, the researchers concluded that a rise in enkephalin occurred when the rats began to feed on M&Ms. The scientists studied changes in the neostriatum of rats when they were “at rest, hungry, offered food, feeding and after eating.” The scientists observed that when the enkephalin rose, the rats ran to eat. When they were “full” the rats immediately stopped eating. When the enkephalin rush ceased, the rats’ compulsion to eat also stopped.

During the second study, the researchers stimulated neostriatum by injecting an opioid into it. The result was equivalent to a “68-kilogram human eating three kilograms of chocolate within an hour.” The rats nearly ate 5 percent of their body weight! The rats had to be removed from the M&Ms because they showed no signs of ending their eating spree.

The researchers concluded that the stimulation of the neostriatum’s receptors with opioids led to “extreme overeating.” According to Gary Wenk, a researcher at The Ohio State University, “the study is adding another piece to the puzzle of how the reward system works.” The neostriatum activates the opiate system, which “counteracts the discomfort of a swelling waist and encouraging us to have one more bite.” When the neostriatum is stimulated the subject reacts by overeating.

Even overeating comes from the brain and not the stomach!

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  1. sayrest4

    This is very interesting, and is just one way in which the brain can cause over consumption of foods. Another study has shown that a part of the brain called the striatum release feelings of pleasure when we eat foods that we like. However, it has been found that in obese people this part of the brain is less active when eating pleasurable foods. This means that already obese people will need to eat more to get the same feeling they got before they were as heavy. It is the same with drug addicts; the level of pleasure will decrease over time, and the only way to combat this is to consume more.

  2. rawgdog

    Cool post! I think if you generalize the concept portrayed in this article, it touches upon an even greater topic. Namely, how the unconscious mind controls us. There have been numerous studies on this issue, but they all point to the fact that the way we act, the way we are, is essentially not controlled by us. The key evidence for this is the fact that our brains are very sensitive. They will react in ways to, for example, the slightest change in weather that can potentially dictate our personality for the rest of the day, or even week. Here is one such article:

  3. leahna

    This is so interesting!
    It appears the brain is definitely wired to enjoy certain types of food, and according to this article, food companies find the perfect combinations of salts, sugars and fats to keep the loop going:

    The science behind why we overeat is extremely important in fighting the obesity epidemic, and I hope more research is done on the topic in the future

  4. explodingllama342

    This is fascinating. It think research like this, which will help us understand overeating and obesity, is the key to ending the American obesity epidemic. There was a study done on the effects of an “edible stop sign” packed into potato chip containers like Pringles. Basically, the red chip was supposed to tell people to stop eating, and it worked. Without knowing what the red chip meant, most people stopped eating once they reached it. Maybe the red chip helps to block the activation of the opiate system which encourages overeating?

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