A new study suggests obese individuals’ brains generate signals that promote eating even when the body is not hungry.
Although obesity is a result of high intake of energy, it is currently unclear why some people are so prone to overeating and weight gain.
Researchers at University of Turku and Aalto in Finland investigated brain connectivity, to see if there was a link between brain activity and obesity. Different imaging techniques were used to compare the brain activity of obese and lean individuals in different situations.
Functional MRI brain scans were used to monitor brain activity in response to seeing pictures of food. The Finnish team found that obese subjects’ reward systems were more activated and responded more vigorously to food pictures, for both “appetising” high sugar foods like cake and bland food. The responses in the opposing frontal cortical regions responsible for personality expression and controls decision decision making,were reduced in these subjects too. By contrast, the healthy individuals showed a significant difference in brain activity between appetizing and bland food, and showed a normal amount of activity in the prefrontal cortex.
Obese individuals also showed higher glucose metabolism in brain reward areas than lean individuals. Along with fMRI, PET scans were used to measure this effect in participants during conditions when their bodies were not physically hungry.
More so, obese individuals even showed high brain response to pictures of food and less activity in areas that control appetite and encourage satiety.
According to Professor Lauri Nummenmaa, adjunct professor at University of Turku said “the result suggest that obese individuals’ brain might constantly generate signals that promote eating even when the body would not require additional energy intake.”
“It highlights the role of brain in obesity and weight gaining.The results have major implications on the current models of obesity,but also on development of pharmacological and psychological treatments of obesity,” she added.
Defects in brain activity have been linked to obesity in past studies. Functional imaging studies have shown sub-components of the brain’s reward circuit contribute to processing of food pictures, and dysfunction of this circuit can be associated with both obesity and drug addiction.
However, more studies are needed to be done to find out which factors influence overeating.
Image by Sandra Cohen-Rose and Collin Rose, on Flickr