Many people are aware of the obesity epidemic in the United States. Many people also associate obesity with extreme over-eating and rare exercise. Recently, researchers have found that obesity may be about more than just an unhealthy lifestyle. Contributing authors to the article Is Obesity a Brain Disease? argue that there are many signaling pathways in the brain that control and regulate hunger and appetite. This specific article is a review article of multiple studies that try to link actual brain signal pathways to reasons for explaining weight gain that can be linked to obesity.
One main point the article makes is that over-eating/over-nutrition is not just a choice. Some may look at that statement and disagree, but pathways in the brain have been found that show the brain is very connected to and partially responsible for the choices people make in relation to eating. The article states that predisposition to high fat diets in the womb and as a child makes them more appealing to people at older ages and actually can influence the food choices they make for their life. These high fat diets have also been linked to cognitive defects in the brain. While the article talks about the relationship between obesity, unhealthy diets, predisposition to obesity, genetics, and brain pathways, it can be hard to decide which is to blame. It is also difficult to decide which comes first, the obesity being induced by over-eating or over-eating being induced by brain function which then leads to obesity. The story is quite complicated. In my opinion the 3 most interesting things learned from this paper and this week’s discussion in class are: the positive effect of health foods, the negative effect of dysregulated sleeping, and a specific neuron called POMC and its role in regulating hunger.
Eating healthy foods that contain a high amount of fiber is really great for a person in multiple ways. Not only does it provide the body with necessary nutrients, but it also makes the body feel fuller for a longer amount of time compared to sugary and unhealthy food. It works to make the body feel full by reducing gastric emptying. It also is able to help increase hormones that curb appetite, for example glucagon-like peptide 1. This specific protein is able to curb appetite by decreasing the satisfaction the brain feels by food. This is really awesome and beneficial to society because eating healthy can do so many great things for a person, to both combat obesity or to remain healthy.
While healthy eating shows the link between obesity and brain function, I think sleep regulation and its link to weight gain/obesity really helps to show that obesity might be able to be considered a brain disease. Most people know the effect on their brain when they experience and irregular or disrupted sleep pattern. The brain is groggy, prone to headaches, and sometimes is slow to respond. This is also expressed in pancreatic insulin release. When the brain is tired and fatigued from irregular sleep, the pancreas is unable to release insulin to respond to the increased blood sugar after a meal. When this happens, the glucose is more likely to be stored instead of metabolized for energy. The body works on a 24-hour circadian clock, which is usually common knowledge, but a recent study from Vanderbilt University discovered that insulin too is able to function on a 24-hour cycle. Dysfunction in sleep and insulin release can be negative for people because it leads to unnecessary storage of glucose, slower metabolic rate, and a decreased rate of calorie burning during resting periods.
The third, and most direct, connection to obesity being a brain disease has to do with special neurons called POMC neurons. These neurons release a chemical called proopiomelanocortin which helps to decrease appetite. It uses the adrenal gland of the sympathetic nervous system to secrete its hormone. One other important hormone involved in appetite regulation is leptin. Leptin is able to alter the activity of these neurons because it is a chemical that signals fullness to the brain. Leptin activity has been seen to be lowered in obese people. This causes a negative cycle. If leptin isn’t working correctly, it can’t correctly signal to the POMC neurons to help inform the brain that the body is full and that it needs no more food.
It is a very unfortunate situation that obesity seems to be such a vicious cycle linked with both the brain and the fact that Americans, for the most part, have a reasonably unhealthy diet. The important thing to do with this information is to brainstorm solutions to the problem. One major problem the US is faced with is the price of health foods. Fresh fruits and vegetables are much more expensive than frozen or canned one. But they contain much more nutritional value. For struggling families, canned or frozen foods may be the only thing they can afford. Eating unhealthy leads to the habit of eating unhealthy, this has major effects in the brain and hormones of a person.
While it may seem like a good idea to target one of the molecules involved in hunger signaling, people in the US (and likely around the world) eat even when they aren’t hungry. Hunger doesn’t seem to be the actual problem. The public needs to be educated on the possible long term effects of obesity, healthy food choices, and the negative things happening to their body when they make unhealthy choices regarding food and eating.
