Obese people could become food addicts

New York -- Obese people may become addicted to food in a similar way that a drug addict is hooked onto drugs, says a new study that examined the brain scan of a few obese people.

Gene-Jack Wang and colleagues at Brookhaven National Laboratory in New York studied seven obese people who were fitted with electrical devices designed to fool them into feeling full by making their stomachs stretch, reported the online edition of New Scientist.

The implanted devices, known as "gastric stimulators", provide low-level electrical stimulation to the vagus nerve, which runs from the stomach to the brain.

When the device is switched on, the vagus nerve stimulation causes the stomach to expand and produce peptides that sends a message of "fullness" to the brain.

"We know that if we eat, our stomach sends a signal to the brain via the vagus nerve. The ingredients of food touch the wall of the stomach and the signal goes through to the brain to say 'eat more' or 'eat less'," explained Wang.

"But we wanted to know which area of the brain the signal goes to," he said.

So the participants were given radioactive sugar so that they could use a scanner to see which parts of the brain were active, by tracing where the sugar was metabolised in the brain.

The seahorse-shaped parts of the brain called hippocampus were activated in the people the same way it gets activated in drug edicts when they crave for cocaine, the researchers said.

"It (The hippocampus) is the area related to memory and the reward system. The areas lighting up were areas activated in drug addicts. It's very similar to what triggers the craving for cocaine," said Wang. So despite receiving the "full" signal, they still have the craving for more.

The findings help explain why it is so difficult to retreat from obesity. "We now know the decision to eat involves emotions and the cognitive system too. This study shows how the brain tries to manipulate the body and not the other way around," Wang noted.

It is difficult for an obese person to diet because they can't suppress the craving to get their next "fix" even when physiologically, they're getting a "full" signal from the stomach, the researcher added.

Such people may continue to feel hungry, even when they have eaten an amount that would satisfy the hunger of a healthy person.