Let’s face it, when you see someone who is heavy set the first thought that you probably have is that their excessive weight is due to a lack of will power or laziness, but what if I told you that the root of their weight gain is actually caused by a diseased state of the brain? There has been recent research that says that obesity may be more than just a lifestyle problem, but a problem in the chemical pathways in the brain dealing with the consumption of food.
One of the major chemical pathways that is usually dysfunctional in an individual who is overweight is the reward pathway that is activated after the consumption of food. This pathway normally is activated when there are any calories in your intestines, which then eventually activates the release of dopamine in your brain, which is the major neurotransmitter responsible for the feeling of pleasure we often associate with the consumption of our favorite foods. The major chemical that allows this pathway to flow smoothly is found in the intestines and is called OEA (oleoylethanolamide). OEA is normally created in the presence of lipids, or fats, in the diet and following their synthesis they activate one of the major nerves in the body that travels to the brain known as the vagus nerve, where it then triggers the release of dopamine, and gives us that satisfied feeling. OEA regulates feeding in and body weight in vertebrates by way of this dopamine reward system because the dopamine release in the brain is a signal for us to know we have eaten enough. This reward pathway can become dysfunctional if for some reason an individual’s level of OEA upon food consumption is below normal. If OEA levels are lower than normal in the intestines it would require an increase in the amount of food consumed in order to increase the levels of OEA enough to trigger a sufficient release of dopamine to cause that satisfied feeling that results in a cessation of food consumption. This increase in the amount of food needed to trigger this reward pathway obviously would lead to over-eating resulting in unwanted weight gain, but because of how this pathway works the person would feel that they needed to consume this extra food because without it they do not get that satisfied feeling after eating. There are a couple of ways that one’s OEA levels can become decreased: a genetic mutation encoding for the production of OEA in the body, or a diet consistently high in fat. Since a majority of people with low OEA are due to a high fat diet I will focus on how this kind of diet affect your reward pathway. Essentially what a high fat diet does is that it decreases your body’s sensitivity to the presence of lipids in your digestive tract which causes your body to produce less OEA. This leads to higher levels of fats needing to be consumed in order to achieve normal levels of OEA to trigger you food reward pathway in your brain. This tolerance to fat in the digestive tract is very similar to what is seen in many addictive behaviors such as drinking and drug use, in that in order to achieve the same “high” more of the substance is required, and in our case the substance being abused is fat. In the United States fat consumption is at an all-time high, so it is no surprise that we see this type of problem in a large portion of our population considering how much fast food and other high fat foods are major staples in our everyday diets.
Now the next time you see or know someone who is overweight make sure that you consider that their weight gain is likely due to more than their lack of motivation to go hop on a treadmill or will power to eat better they may have a chemical imbalance in their nervous system that may not be so easy to overcome.
Who's to Blame for Obesity?
