Glucose levels affect brain's ability to make reasonable shopping choices

The free samples merchants offer at high-end grocery stores may be delicious, but they may also discourage shoppers from buying more.

The free samples merchants offer at high-end grocery stores may be delicious, but they may also discourage shoppers from buying more. In fact, restaurant and grocery store owners may reap greater sales from a hungrier cross-section of customers.

Researchers from Yale University and the University of Southern California recently conducted a study evaluating the effect of an empty stomach on impulse buying, such as high-calorie junk food.

The researchers controlled participants' glucose levels in a functional MRI scanner and found heightened brain activity in the prefrontal cortex - the region devoted to logical and reason-based functions - when glucose levels were normal. When glucose levels dropped, however, activity surged in the hypothalamus and thalamus regions - the areas devoted to emotions, rewards and addictive behavior.

"This happens because it's an important survival strategy: When glucose levels wane, it's a signal that the body is running low on fuel necessary to survive; the response is to remove any barriers to eating," reports Alice Park for Time magazine.

From a consumer's standpoint, it may be a good idea to eat before you go shopping. Otherwise you may come home with a few too many Twinkies.