Understanding the urge to eat: visual cues are more powerful than previously suspected – Nutrition

Understanding the urge to eat: visual cues are more powerful than previously suspected – Nutrition – Brief Article

Lacey Beckmann

THE MERE SIGHT OR SMELL OF YOUR FAVORITE food can trigger an urge to eat that is distinct from food cravings. This helps explain why satiated people continue to eat: They are powerless to resist the image of food.

Scientists know that increased levels of dopamine, the neurotransmitter linked to pleasure-seeking behavior and feelings of reward, are associated with the desire to eat. Now, Nora Volkow, M.D., associate director of Brookhaven National Laboratories in Upton, New York, has demonstrated that the sight of food alone boosts dopamine levels in the dorsal striatum, a part of the brain that regulates the basic drive to eat. This contradicts findings that dopamine levels rise only in the pleasure center of the brain.

But Volkow says this makes sense because “the brain evolved so that when you find food, you eat it, no matter what. It’s a reflexive response to ensure that you eat enough to survive.”

Volkow deprived 10 healthy, nonobese subjects of food for 16 to 20 hours. She then exposed them to their favorite food but did not allow them to eat, a situation that mirrors our constant exposure to advertisements for food.

“These were people who could control their food intake, but they were responding to a strong signal,” explains Volkow. “And that signal was associated with the drive to eat.”

To observe fluctuations in dopamine levels, Volkow administered the stimulant Ritalin. The `drug amplified subjects’ response to the sight of food, a surprising and counterintuitive finding, given that stimulants are known to suppress appetite. But Volkow argues that stimulants enhance conditioned responses under unusual circumstances, such as a laboratory setting.

The results were published in Synapse.

COPYRIGHT 2002 Sussex Publishers, Inc.

COPYRIGHT 2002 Gale Group