Obesity is frequently demonized as a disease of laziness – one that people could avoid if they would only get off the couch and eat healthier. Recent research, however, has identified several brain-related components to this disease, possibly enough to categorize it as a brain disorder. While it is true that some individual responsibility is required for overcoming obesity, several other factors must be understood in order to really tackle this issue.
Much of the brain dysfunction that occurs in obesity does appear to come as a result of high-fat diet. Chronic intake of high amounts of fat can inflame and damage some parts of the brain, including the hypothalamus, which controls hunger (among other homeostatic processes, like sleep). Inflammation in the rest of the brain will eventually lead to a cascade of events resulting in loss of memory function. Overconsumption of carbohydrates, another obesity-associated eating behavior, can lead to insulin resistance, which has been shown to have a negative effect on cognition and induces type 2 diabetes. But if an unhealthy diet causes obesity and so many other health issues, how can people not be expected to assume more responsibility for themselves?
First to consider are the social issues linked with obesity. There is the obvious issue of fast food and other generally unhealthy food being usually cheaper than more nutritional food. This especially affects low-income communities: one 2010 study found that BMI and income were inversely related, indicating a correlation of low wages to increased risk for obesity. Not only are there many factors that can predispose people to being obese, but once weight gain begins, it can be hard to go back. This is especially true when exposure to high-fat foods begins early in life. For example, rats exposed to a high-fat diet when nursing or pregnant leads to overweight offspring. Additionally, another study found that when rats are exposed to the same type of diet during the postnatal growth period, they tend to favor high-fat foods in their adult lives, leading to an increase in risk for obesity.
Perhaps the most interesting element involved in obesity is the modulation of metabolism and intestinal signaling by microbiota which naturally occur in the digestive system. Bacteria play a role in the speed by which food is transferred from the mouth through the rest of the gut, an activity which happens more quickly in obesity. This leads to feeling hungry sooner after eating as well as altered absorption of certain nutrients. Interestingly, a study found that by simply transferring bacterial cultures from obese mice to nonobese mice, they developed symptoms associated with metabolic syndrome – one of which is obesity.
Perhaps it can be said that obesity begins with poor nutritional choices – but these choices can be influenced by society and perpetuated by alterations to brain morphology and predisposition to metabolic disorders. By understanding the complexities underlying obesity and how societal pressures, differences in biochemistry, and even nonhuman microorganisms can affect the body’s response to how it handles overnutrition (too many carbs, too much fat, etc.), we can begin to make obesity more about personal medicine rather than personal morality. After all, we don’t treat depression as the result of an unwillingness to be happy; while this can perpetuate the illness, it is accommodated for and worked around in current therapies. If obesity could be resulting from a combination of effects not directly related to personal choice, why can’t we treat it the same way?
For more information on gut bacteria, a great summary can be found here.
Obesity: What happens when you can't trust your gut
