Junk-food junkie? Blame your brain

Consumer Reports News: September 19, 2011 03:53 PM

A drop in blood sugar levels causes an area of your brain that regulates emotions and impulses to temporarily go haywire, especially if you're overweight, triggering an intense desire for high-calorie foods. That's according to a study published online today in the Journal of Clinical Investigation.

Researchers from Yale and the University of Southern California at Los Angeles controlled blood sugar levels of five obese people and nine normal-weight ones as they underwent MRI brain scans. When blood sugar levels dropped, the obese people experienced intense cravings for high-calorie foods, like ice cream, and the cravings persisted even when blood sugar levels returned to normal. Normal-weight people also experienced cravings, but they stopped as soon as the levels normalized.

The brain scans showed that a drop in blood glucose levels was sensed by a region of the brain called the hypothalamus, which in turn activated two brain regions associated with reward, the insula and the striatum, triggering a desire to eat. In normal weight people, another brain region—the prefrontal cortex—ultimately put the brakes on that desire, as blood sugar levels dropped. But in obese people, that region seemed unable to rein in the striatum.

Bottom line: While your brain doesn't have an "off" button, the authors of the study suggest turning to healthy snacks rather than high-calorie ones to help maintain glucose levels. The next time you get a junk-food craving, reach for fruit, yogurt, dry-roasted nuts, or baked tortilla chips.

Need more help? See our tips on how to eat right without even trying and six small ways to keep off the pounds.

Source
Circulating glucose levels modulate neural control of desire for high-calorie foods in humans [The Journal of Clinical Investigation]

—Ginger Skinner