Q&A: Were You Born to Be Obese?
Possibly, Batterham says. She's now looking at lifestyle factors that control ghrelin and also exploring whether lowering ghrelin levels with drugs might help.
Q: Can you give some background on FTO?
"Since 2007, it has been known that people who carry two copies of the obesity-risk variant form of the FTO gene are 70% more likely to be overweight or obese," Batterham says. These people also ate more calories and preferred high-calorie foods, according to research. But no one knew why.
Batterham's team studied 20 men. Half of them had two copies of the FTO variant. The other 10 had a version linked with lower obesity risk. The men rated their hunger before and after eating and had their ghrelin levels measured. The researchers also did brain scans to compare how the brain responds to food images and ghrelin levels between the two groups.
Q: What did you find?
Healthy-weight people with two [modified FTO] copies "fail to suppress their hunger appropriately after eating, so they feel more hungry," Batterham says. After a meal, she says, they have higher levels of ghrelin.
"Their brains respond differently to pictures of food in both the fasted and fed states in key brain regions known to regulate appetite, reward, and motivated behavior," she says. Key regions of the brain that control eating behavior respond to the ghrelin circulating. People with two copies of the FTO variant find high-calorie food images more appealing after a meal than those with the low-risk variant.
Q: What would you tell people with these genetic variants so they don't get discouraged or feel doomed to obesity?
''There is some evidence that telling people that they are at risk and will find it harder to control their weight leads to increased motivation to exercise," Batterham says. Dispensing simple advice, such as ''don't even look at the dessert menu,'' may also help.
"We have shown [in other research] that dietary factors and lifestyle may modify the genetic effects," Qi says. Among the helpful measures are cutting back on sugary drinks and TV-watching time.