High Glycemic Index Food May Trigger Food Addiction

Posted by on Jul 3, 2013
in the category Nutrition

Source Medscape Today

By Kathleen Louden

Consumption of a meal that has a high glycemic index (GI) appears to stimulate key brain regions related to craving and reward, a finding that supports the controversial hypothesis of food addiction, new research suggests.

A new research published online in Am J Clin Nutr. June 26, 2013 found that consumption of a high-GI meal found in refined carbohydrates decreased plasma glucose, increased hunger, and selectively stimulated brain regions 4 hours after eating — a critical time point that influences eating behavior at the next meal.

"We think we have shown for the first time that refined carbohydrates' biological effects can provoke, independent of calories and tastiness, symptoms related to addiction in susceptible people — those who are overweight or obese," said the study's principal investigator, David Ludwig, MD, from Boston Children's Hospital.

Craving Carbs

He said the randomized, blinded, crossover study in 12 overweight or obese men had several strengths over previous studies whose findings also suggested that certain tasty foods might be addictive.

In the new study, participants aged 18 to 35 years consumed, in a randomized order on test days 2 to 8 weeks apart, 2 test milkshakes that had similar ingredients, calories (500 kcal), appearance, taste, and smell.

Participants were not aware which was the low-GI meal (37%) with slow-acting carbohydrate and which was the high-GI meal (84%) with fast-acting carbohydrate, and they reported no preference for either meal.

Additionally, the investigators monitored participants 4 hours after the meal, when the individuals likely would be considering what to eat at their next meal. At that time, participants underwent a final blood glucose test and neuroimaging, and rated their hunger levels.

After eating the high-GI meal, participants initially had a surge in blood glucose level that was 2.4-fold higher than after the low-GI meal, followed by a crash in blood glucose at 4 hours, the authors reported. They also reported excessive hunger 4 hours after the high-GI meal, Dr. Ludwig said.

The investigators looked directly at participants' cerebral blood flow using functional magnetic resonance imaging (fMRI), which allowed them to examine persistent effects of test meals on the brain. "Every single subject showed intense activation in the nucleus accumbens, the area of the brain related to addiction," Dr. Ludwig said.

The results show that highly processed carbohydrates, such as white bread, potatoes, and concentrated sugar, "alter brain activity in ways that make us crave them even more," he said.

Dr. Ludwig said that the initial results send a clear take-home message: "Avoiding highly processed carbohydrates could help overweight people avoid overeating."

Am J Clin Nutr. Published online June 26, 2013. Abstract