The Role of Genetics in Obesity
Updated: Sep 25, 2021
The relationship between genetics and obesity is perceived to be clear. Many people believe that genetics in obesity is the defining factor for why someone became or was born overweight. While that may be true for some, the relationship between genetics and obesity is not always clear. Science has shown that genetics may play a role in obesity; however, like other diseases, it can depend on environmental factors such as food habits and exercise.
Genetics can influence obesity in a way not directly related to the body-- genes can influence behavior leading to obesity. Several studies have found that some genes may play a role in food habits, as these genes increase hunger and make one more susceptible to eating more. An example of a gene that may lead to this is called monogenic obesity. Those with this gene eat abnormal amounts of food and are incapable of stopping themselves from eating large quantities of food, leading to obesity unintentionally.
Another explanation for the role genetics plays in the obesity epidemic today has been the idea that they are “outdated” in a sense. The idea being the genes humans have today are the same ones our ancestors had when the food supply was low. So, now that those same genes are in a world with plenty of food, human bodies gain weight. Data from the National Institute of Diabetes and Digestive and Kidney Diseases shows that obesity in men grew from 10% in 1960-1962 to 35% in 2013-2014. Obesity has been significantly increasing in recent years. But without an evolutionary change in our genetics, the factor of “outdated genes” cannot be controlled.
Considering all these possibilities with genetics, the behavior one exhibits still is of high importance when considering factors behind obesity. Extreme genetic conditions may prevent one from controlling their behavior surrounding eating habits and exercise; however, human genes from the past have not remarkably changed, attributing most obesity today to environmental factors. More specifically, the genetic make-up of the human population has not really changed from the past when obesity was low, but the food supply and the types of food have. The widespread access in many places to the high food supply and inexpensive processed, unhealthy foods has substantially contributed to the obesity pandemic today. Along with food habits, the lack of exercise among a large portion of the population has contributed to the obesity epidemic.
Therefore, obesity, like other health diseases and risks, can possibly be influenced by genes. But unless one has the monogenic obesity gene or some other gene causing inherited obesity, they are unlikely to inherit obesity. The environment one is in, one’s behavior, and the choices one makes regarding food and exercise mostly influence obesity. These non-genetic factors can explain the increase in obesity in recent years that has led to an American Obesity Epidemic.
Sources:
CDC. 2019. Behavior, environment, and genetic factors all have a role in causing people to be overweight and obese. Centers for Disease Control and Prevention. https://www.cdc.gov/genomics/resources/diseases/obesity/index.htm.
CDC. 2019. Other Factors in Weight Gain.
https://www.cdc.gov/healthyweight/calories/other_factors.html.
McAllister EJ, Dhurandhar NV, Keith SW, Aronne LJ, Barger J, Baskin M, Benca RM, Biggio J, Boggiano MM, Eisenmann JC, et al. 2009. Ten Putative Contributors to the Obesity Epidemic. Critical Reviews in Food Science and Nutrition. 49(10):868–913. doi:10.1080/10408390903372599. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2932668/.
Ogden, Cynthia. 2018 Dec 13. Overweight & Obesity Statistics | NIDDK. National Institute of Diabetes and Digestive and Kidney Diseases.
https://www.niddk.nih.gov/health-information/health-statistics/overweight-obesity.