Q&A: Were You Born to Be Obese?
Aug. 1, 2013 -- For people who often feel hungry right after eating, a recent finding about genetics and obesity was, if not welcome news, at least thought-provoking.
People who have two copies of a modified form (or variant) of a certain gene are much more likely to feel hungry after eating a meal, says researcher Rachel Batterham, MD, PhD, of the University College London.
One in six people has two copies of the modified "fat mass and obesity associated" (FTO) gene. That could help explain some obesity. People with this gene have high levels of the hormone ghrelin, which increases hunger.
Batterham and a U.S. expert in genetics and obesity talked about the finding and what it might mean.
Batterham is head of the University College London Centre for Obesity Research and head of Obesity and Bariatric Services at the UCL Hospital. Her study, published July 15 in the Journal of Clinical Investigation, was funded by the Rosetrees Trust and others.
Lu Qi, MD, PhD, is an assistant professor of nutrition at the Harvard School of Public Health.
Q: Can you put this new discovery in perspective with other obesity and genetics findings, since many genes have been linked with body mass index and obesity?
The effect of FTO on obesity, so far, is that it's the most common “genetic contributor to overweight and obesity, and is estimated to affect 1 billion people worldwide," Batterham says.
This is one piece of the puzzle, she says, but possibly a key piece.
Qi agrees. But he cautions that scientists must test many more people to confirm Batterham’s results.
Q: At this point, how big of a role might genes play in obesity?
"From previous studies, it is estimated that 40% to 70% of a person's BMI is inherited," Batterham says, but it's complex and not as simple as just giving a percent.
Overall, the role of any single gene [in obesity] is not big, Qi says. However, if all the obesity-related genes are considered, “the effect would be sizable."
Q: Is it possible to be tested for the FTO variant?
Several companies already offer direct-to-customer testing for variants, including FTO, Batterham says. But she wants to study whether knowing that you have the FTO variant would help people make better lifestyle choices.
Q: If you have two copies of the FTO variant, what can you do to avoid obesity?
More research is needed, Batterham says, but she cited studies showing that aerobic exercise and a high-protein diet may help such people. Results of the research have been mixed, she says.
Behavioral therapy might help people who have the double FTO variant avoid temptation, she says.
Q: Could the new findings, as well as other findings, lead to a treatment?