The Genetics of Obesity

Obesity tends to run in families, signaling a possible genetic cause.

However, the quest to find the “fat gene” is in the early stages, despite advances in scientific research.

What’s much more certain is that habits, such as unhealthy eating and a lack of physical activity, are more likely to contribute to obesity across generations, cultures and households.

“Oftentimes, I see obesity throughout the different generations,” said Anaisys Ballesteros, D.O., who practices family medicine as a member of the Baptist Health Medical Group. “It’s difficult to say if it’s appetite, genetics or metabolism.  But culture is something you pass on to your kids, and that can include eating habits and a sedentary lifestyle.”

Family medicine practitioners and primary care physicians are on the front lines of helping families avoid conditions tied to obesity, especially diabetes, high blood pressure, high cholesterol levels and other factors that contribute to heart disease.

Scientific researchers worldwide are also doing their part with some success. In July, a British-lead research team used a series of tests to determine that people with a certain genetic variation had higher levels of the “hunger hormone” ghrelin in their blood. Previous research has shown that ghrelin can be reduced by eating a high-protein diet, but more tests are needed.

Developing effective obesity drugs has been a challenge for drug makers. No one should take any drug that claims to fight obesity without consulting with their physician, Dr. Ballesteros says. Obesity, or just being overweight, requires a thorough blood workup and physical examination to determine the extent of risk factors that may be present.

“There are some patients that are doing everything right to try and lose weight, but no matter what they do they have a hard time,” said Dr. Ballesteros, who was  also a registered dietitian earlier in her career.

In those patients, thyroid or hormonal issues have to be ruled out. Moreover, the option of undergoing weight-loss surgery is becoming more popular for those who are severely obese and have been unable to get results with diet and exercise alone.

According to the U.S. Centers for Disease Control and Prevention, more than one-third of U.S. adults (35.7 percent) are obese. The obesity rate has more than doubled since about 1980. A BMI (body mass index) of 25 to 29.9 is considered overweight. A BMI of 30 or higher is considered obese.

Up to one in every five children in the U.S. is overweight or obese, and the numbers are rising. Children have fewer weight-related health and medical problems than adults. However, overweight children are at high risk of becoming overweight adolescents and adults.

Dr. Ballesteros notes that any analysis of the obesity epidemic has to include both the role of genetics along with that of the environment. For example, children nowadays spend hours watching television and playing video games, more so than in the past. Sedentary lifestyles with both adults and children play a vital role in obesity.

Genetics, however, will play an increasingly important part of the equation used to battle obesity, Dr. Ballesteros said.

Studies are already focusing on members of a family or a cultural subset that buck the obesity trend. Not all obese people have the same body fat distribution or suffer the same health issues. And not all members of a family, where obesity is an issue, have a weight problem.

This diversity occurs among groups of the same racial or ethnic backgrounds, and even within families living in the same environment. This variation is a big indication that genes play a role in the development of obesity.

“It could be genetics, but lifestyle issues we can treat now,” Dr. Ballesteros said. “If I see a pattern with my patients, I take a thorough history and find out what and how much they’re eating. Often, I see that the parent s of my patients already have complications, such as hypertension and diabetes ,from obesity. But I also see that they are becoming much more receptive to my suggestions as they become better educated about the risks.”