What’s Genetics Got to Do with It? The Science Behind Obesity

In 2008, Texan Mayra Rosales was accused of brutally murdering her sister’s son. But this case had a twist—prosecutors claimed that Mayra, who weighed over a thousand pounds, fell on the boy and crushed him under her massive figure. Though it was eventually revealed that Mayra’s body was so immobile that it was impossible for her to have committed the crime (she had falsely confessed to protect her sister), the case earned Mayra the nickname “half-ton killer.”

But Mayra’s story is about more than just the tragic loss of her nephew—it also highlights a startling problem of obesity that many developing nations face today. According to the Center for Disease Control in 2008, the estimated annual medical cost of obesity in the United States was $147 billion, and medical costs for people who were obese were $1,429 higher than those people of normal weight. Obesity also inflates Medicare and Medicaid spending by nearly $62 billion dollars. On an individual level, obesity-related conditions include heart disease, stroke, type 2 diabetes and certain types of cancer, some of the leading causes of preventable death.

Many people equate obesity with carelessness, overindulgence, laziness, and gluttony. And while it is very true that little physical activity and continual consumption of unhealthy foods will not bode well for anybody, various scientific literature suggests that perhaps there are more than just external factors that cause obesity. In fact, several scientists hold the view that genetics plays a huge role in obesity.

An article published on March 12th, 2014 in HealthDay News cites several geneticists who claim to have very recently pinpointed an obesity gene that controls body mass and regulates composition: IRX3. In their experiments, they found that mice that lacked the gene IRX3 were nearly thirty three percent lighter than their counterparts, who had the gene. According to Marcelo Nobrega, the scientist who headed the investigation, it’s taken so long to reach this conclusion because researchers have been studying the wrong gene the entire time. Previous investigations into the genetics of obesity claimed that mutations on the gene FTO led to obesity, but there has been no evidence that said mutations actually change the functioning of the FTO gene.

Put simply, mutations that predispose one to obesity occur within the FTO gene but don’t actually affect that gene. Instead, they trigger a reaction in the IRX3 gene, which creates an overproduction of the IRX3 protein in the brain. This impacts the functioning of the hypothalamus of the brain. Why is this important? The hypothalamus regulates metabolism and appetite in the body, and something that impairs the functioning of the hypothalamus may trigger weight gain and eventually, obesity.

This information is crucial in helping scientists determine which cells are being affected by IRX3, and eventually will allow them to develop drugs to block the genetic obesity-causing effects. Perhaps in the future, genetically induced obesity will be eliminated once and for all. That’s not to say that society should place all the blame of obesity on genetics. Various changes in eating and lifestyle habits can lead people to healthier lives, and even more drastic measures like gastric-bypass surgery can drastically reduce weight in obese people.

Today, Mayra weighs in at around two hundred pounds, down over eight hundred pounds from where she was six years ago. The “half-ton killer” was no killer in 2008, and in 2014, is half-ton no more.

About Mr. Mohn

Biology Teacher

This entry was written by Michelle C. and tagged . Bookmark the permalink.

Leave a Reply

Your email address will not be published. Required fields are marked *