Brings a New Meaning to Ground Breaking News!~
A ground-breaking brain-imaging study at the U.S. Department of Energy’s Brookhaven National Laboratory shows that men, but not women, are able to control their brain’s response to their own favorite foods. The study, which will be published online by the Proceedings of the National Academy of Sciences the week of January 19, 2009, may help explain why rates of obesity and eating disorders are higher among women than men, and why women typically have more difficulty losing weight.
Our findings may help us understand the neurobiological mechanisms underlying the ability to control food intake, and suggest new pharmacological methods or other interventions to help people regulate eating behavior and maintain a healthy weight,” said Gene-Jack Wang, lead author on the study. “The surprising finding of a difference between genders in the ability to inhibit the brain’s response to food and hunger will certainly merit further study.”
The scientists used positron emission tomography (PET) scanning to monitor brain activity in 13 female and 10 male volunteers. In this method, a form of glucose “tagged” with a radioactive tracer molecule is injected into the blood stream while subjects lie in the PET scanner. The scanner tracks the tracer’s signal to monitor the uptake and use of the glucose by various regions of the brain. All study subjects were of normal body weight and had fasted for nearly 20 hours before each of three separate scans, performed in random order.
Each brain image shows the change in brain metabolism when subjects were asked to inhibit their response to food during food stimulation compared with when they were not told to inhibit their response. Two brain sections at different levels of the brain are shown for each group (women, men, and women vs. men). Top row, women: No color indicates that women had no significant differences in brain activity between the two conditions. Middle row, men: Blue colored areas were significantly less active when men were told to inhibit their response to food than they were without inhibition. Third row, women vs. men: Orange color indicates areas where men showed greater decrements with inhibition than women. These brain regions are involved in emotional regulation, conditioning, and the motivation to eat.
On one scan day, subjects were presented with their favorite foods — from bacon-egg-and-cheese sandwiches to pizza, cinnamon buns, barbecue ribs, and chocolate cake — warmed, if appropriate, to enhance the enticing aromas and taste. During the scan, subjects were asked to smell, taste, observe, and react to the food, but not eat it. On another day, they were instructed to inhibit their desire for food prior to being tempted with the same foods. A control scan with no food was performed on another day.
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