Eat less, exercise more: This simple advice can go a long way in battling obesity. However, recent studies indicate some of us may have an easier fight than others—not only due to environment, but also due to genes and race.
“I think people would be more comfortable if I were to say, ‘Differences in obesity are a consequence of socioeconomic factors,’ ” says Jose R. Fernandez, Ph.D., assistant professor of nutrition sciences. “But if you bring in genetics, it becomes more complicated, because we cannot change our genes.”
Race is not a simple black-and-white issue, either—most Americans identify themselves with one particular ethnic group, but in fact we are highly mixed. This can be studied through genetic information by a technique called “genetic admixture” and the quantification of genetic admixture serves as the backbone of Fernandez’s research.
The first step of the genetic admixture estimation is to identify as reference points several markers that differ among European, African, and Amerindian populations, representing the three major groups that interacted during the period of colonization of the New World. Using this information, Fernandez and his team were able to calculate the estimated genetic admixture for a given subject—for example, 80 percent European, 15 percent African American, and 5 percent Native American.
The genetic admixture was then placed in a statistical model to declassify race, adjusting for environmental factors such as socioeconomic status and education level, which essentially declassified race. When cross-referenced with measurements such as body fat, fat-free mass, and bone density, the results supported certain trends already established by the Centers for Disease Control (CDC). For instance, a higher African- American admixture corresponds to higher levels in all three of these categories—in other words, the more African genetic admixture one has, the greater the likelihood of having more fat, lean, and bone mass. This may result in greater prevalence of obesity, holding all other environmental and behavioral factors constant.
“We knew there were differences among races in terms of obesity,” Fernandez says, referring to the CDC data. “The question was why.” The next question is: How can this information be used to solve our growing obesity problem? After all, even the most groundbreaking scientific research is meaningless without effective dissemination and implementation in the real world, and Fernandez is acutely aware of this fact.
“One of the components that we need to improve in the research community is the translational aspect,” he says. “Bringing the data to the public and teaching them how to use it is a vital component in everything we do.”
This explains his recent focus on the genetics of obesity and diabetes in children. The AMERICO Study (Admixture Mapping for Ethnic and Racial Insulin Complex Outcomes) measures insulin responses to glucose across racial categories. It also relies upon information about diet and exercise collected from various questionnaires.
The short-term goal is to identify at risk admixtures, while the long-term goal is to not only translate the data but also develop specific early-intervention strategies. That’s why the focus on children is so important—they can develop healthy lifestyle choices and, hopefully, carry those into adulthood.
Of course, the ultimate success or failure of these initiatives will be decided at the individual level—and it’s important to understand that having a certain ethnic background doesn’t necessarily mean one will develop certain conditions.
“There’s no such thing as genetic determinism in complex diseases,” Fernandez notes, “only genetic predisposition. I really believe we’re developing a consciousness about these issues, which is a very positive development.”