Photos: Getty Images
You know that little voice in your head that looks at a big plate of fresh cookies and whispers, "You'd better eat just one?" Turns out, in people who are already obese, it may be a teeny-tiny voice or missing altogether.
That's the finding of brain researcher Dr. Antonio Convit, a professor of psychiatry and medicine at the New York University School of Medicine and the Nathan Kline Institute, reports New Scientist magazine. Convit and others have long been aware that type 2 diabetes is associated with memory difficulties, the result of a diabetic's inability to increase fuel for the brain to conduct the kind of problem solving that will, for instance, allow them to remember where the heck they put their car keys.
Figuring something similar might occur in people who were obese, Convit looked at the brains of 44 middle-aged obese people and 19 lean ones, using MRI's and other tests.
What he found were changes in the obese subjects in two parts of the brain that play major roles in eating. In obese people there was more water in the amygdala, which, among its functions, regulates feeding behavior. He also found that the orbital frontal cortex of the brains of obese people was smaller, which meant it had less ability to perform one of its key functions -- inhibit automatic responses -- such as the impulse to eat that whole plate of cookies.
"The brakes on the system are dysfunctional," Convit said. "If you're damaging the parts of the brain that are essential to controlling feeding behavior in the first place, it might be a vicious cycle."
"You're throwing gas on the fire," he said.
The study did not look at whether obese people already had these conditions in their brains and whether this was what caused the obesity, or, in contrast, whether the obesity caused them. Based on animal studies, however, Convit's best guess is that obesity causes the initial brain changes.
The good news, Convit believes, is that, like the cognitive improvements found in diabetics once their diabetes is under better control, brain changes in obese people are probably reversible as a person loses weight. "Very little weight loss can lead to large heath improvements," he said.