Brain scan can predict weight gain

Scans of a brain region linked to both pleasure and addiction could help predict whether a person will gain weight or have sex in the next six months, a new research has suggested.

Researchers at the Dartmouth University in the US found that young women whose nucleus accumbens, an area buried deep in the brain, reacts strongly to pictures of appealing food are more likely to gain weight in the next six months.

Likewise, when the region responds strongly to sexual imagery, women are more likely to be sexually active within the next six months, the researchers said.

“This study is nice in a sense in that it’s one of the first ones to actually tie your brain responses to more long-term measures of behaviour,” study researcher Bill Kelley, a psychologist at Dartmouth, told LiveScience.

In the long run, Kelley added, the brain’s reward system is likely to be only a piece of the puzzle. How good a person is at overriding that system through willpower will matter too, he said.

Certain health conditions, including bulimia and obesity, have already been linked to high nucleus accumbens activity in response to food-related cues.

In the study, published in The Journal of Neuroscience, Kelley and his colleagues wanted to find out if there was any predictive power to such linkages. So they recruited 58 female college students and calculated their body mass index (BMI).

Next, their brains were scanned using functional magnetic resonance imaging (fMRI) while the young women viewed a series of pictures of delicious-looking food, environmental scenes, people and some erotic images.

The scanning measured blood flow to their brain regions, offering a real-time picture of changing energy use in the brain at any given moment. Six months later, the same women were again called for another weigh-in and further surveys. It was found the women whose nucleus accumbens responded more strongly to pictures of food were the ones most likely to gain weight over the next six months. And those with a strong nucleus accumbens reaction to erotic images were more likely to report at least one sexual partner during that period, the researchers found.

Importantly, these reactions were behaviour-specific, the researchers said. Weight gain was linked only with a nucleus accumbens response to food pictures, not to sexy images or neutral environmental scenes.