The 'Obese Brain' Fuels Overeating

ORLANDO, Fla. – Obesity may cause changes to the brain that actually fuel more overeating, recent research suggests.

Such a vicious cycle may be a reason why people find it especially hard to lose weight once they become obese, said Terry Davidson, director of the Center for Behavioral Neuroscience at American University in Washington, D.C.

In a talk here at the American Psychological Association meeting, Davidson said that high-sugar, high-fat foods often found in a Western diet have been shown in animal models to impair the function of the brain's hippocampus. This brain area is important for memory, and is thought to help control food intake. Rats that have their hippocampus damaged will eat too much and gain weight, Davidson said.

The hippocampus also helps suppress unwanted thoughts or memories. If the hippocampus is impaired in obese people, they may find it hard to suppress thoughts of food, and as a consequence, more likely to eat food when they see it, Davidson said.

If the results from animal studies hold true in people, researchers may be able to develop new therapies to help obese people lose weight.

"We've identified a potential area of the brain that should be a target for either psychological or pharmacological therapies," Davidson said. If the damage to the hippocampus can be repaired, "it should make it easier for people to control their [food] intake," Davidson said.

Researchers have identified several ways that high-fat and high-sugar foods may hurt the hippocampus. In one study, rats fed a Western diet developed a leaky blood-brain barrier, said Scott Kanoski, a behavioral neuroscientist at the University of Pennsylvania. If the blood-brain barrier is impaired, it would allow toxins to enter the brain, and potentially damage the hippocampus, Kanoski said. It could also allow immune system proteins to enter the brain, and cause brain inflammation, Davidson said.

Studies conducted by Kanoski and colleagues on rats have also found that a Western diet decreases the levels of a protein called brain-derived neurotrophic factor, or BDNF, in part of the hippocampus. BDNF is known to be important for memory function, Kanoski said.

An increasing amount of research has also linked obesity to cognitive impairment in people, Davidson said. It may only be a matter of time before cognitive impairment, such as dementia, is considered a health consequence of obesity by government agencies, Davidson said.

Pass it on: The Western diet may not only cause obesity, but also harm the brain in a way that leads people to eat more.

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