How Gray Matter Affects Fatty Matter

Obesity may have complex roots in how brains interpret food messages in the environment

(RxWiki News) Brains work in mysterious ways, influencing diet more than people might realize. It might scientifically be a lot tougher for one person to turn down a brownie sundae than another.

A new paper looking at past studies on brain research and the signals that seeing or eating food sends to the brain reveals that obese individuals may be more susceptible to becoming overweight because of the way their brains react to high-calorie and/or fatty foods.

"Plan healthy meals ahead to avoid accidentally overeating."

Alain Dagher, PhD, of the Montreal Neurological Institute at McGill University, has written a review of research that discusses the patterns being seen in brain images of lean and overweight people.

The studies Dagher looked at included ones where neuroimaging - or studying images of a person's brain and neuron activity through tests like MRI scans - revealed insights about how a person's brain reacts when it encounters certain types of foods and/or when a person eats certain foods.

Among the discoveries scientists have made are that the brain has regions dedicated to appetite control and that appetite can be affected by both learned behavior and motivational signals in the brain.

The association between eating and feeling "rewarded" in the brain has also helped scientists understand more about the complex causes underlying obesity, Dagher found.

"Patterns of brain activity thought to underlie obesity have emerged," Dagher writes. "In particular, there has been great interest in looking at the brain for the source of vulnerability to overeating in a world of cheap, abundant, high-calorie food."

For example, Dagher found that overweight and obese people show stronger brain signals when they are presented with sweet or fatty foods, which in turn motivates them to eat.

In general, Dagher, found, obese individuals may be more susceptible to becoming overweight in the first place because of the way their brain influences what they eat, when they eat and how much they eat.

"The emerging imaging literature supports the view that although there is not a single pathway leading to obesity, it is a neurobehavioral problem: a disease that results from a vulnerable brain in an unhealthy environment," Dagher said.

That unhealthy environment includes fast-food advertising - which requires more attention much in the same way that scientists began paying attention to the impact of cigarette advertising in the 1990's, Dagher said.

"The demonstration that humans are sensitive to food cues, such as advertising, especially when these food cues are associated through past experience with high-calorie foods, cannot be ignored," he said.

"The neuroscience of appetite will be called upon to inform and justify the public policy decisions that will be needed to address this most significant public health problem," he added.

Although a number of the studies Dagher reviewed were small and/or had elements that could have biased the results in some directions, he said the overall picture that arose from the review makes it clear that additional research into this area is necessary to deal with increasing rates of obesity.

The research was published online April 5 in the journal Trends in Endocrinology and Metabolism. Dagher receives funding from the Canadian Institutes of Health Research, the FRSQ (a Quebec health research fund), the National Institute on Drug Abuse,the Parkinson Society of Canada, the Institute for Research on Pathological Gambling and Related Disorders and Unilever PLC.

Review Date: 
April 3, 2012