Shedding light on why some people tend to overeat, a small study suggests that the brain responds differently to a full stomach depending on a person's weight.

by Amy Norton

In a brain-scan study of 18 volunteers, researchers found that normal-weight and overweight participants had different patterns of brain activation in response to 'fullness' cues from the stomach.

Specifically, overweight individuals had less activity in a brain area called the left posterior amygdala. The amygdala is involved in regulating emotion, and has been thought to play a role in appetite and eating.

The findings offer the first evidence connecting the left amygdala to feelings of fullness, according to Dr. Gene-Jack Wang, the lead investigator on the study and a researcher at Brookhaven National Laboratory in Upton, New York.

Furthermore, the results suggest that lesser activation in this brain region helps explain why some people continue to eat when their stomachs are moderately full, explained Wang.

He and his colleagues report the findings in the journal NeuroImage.

For the study, the researchers used expandable gastric balloons to create stomach distention in each of the study volunteers -- simulating that full feeling that comes with a meal. They also used functional magnetic resonance imaging (fMRI) to visualize the participants' brain activity as their stomachs were distended.

In general, the researchers found, overweight volunteers felt less full than their normal-weight counterparts did when their stomachs were moderately distended. Overweight participants also showed less activation in the amygdala.

The results suggest that the amygdala could potentially be a target for weight-loss therapies, according to Wang. That could mean medications or even behavioral therapies, he told Reuters Health.

In other research, Wang explained, he and his colleagues found that some people could suppress their desire for food in the face of tasty treats, and that, in turn, changed the activation in their amygdala.

The implication, he said, is that behavioral therapy might modulate amygdala activity and appetite in some people.


Source: Reuters

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