Although the idea of ‘food addiction’ has always been considered a controversial one, new research suggests that eating a meal that has a high glycemic index (GI) appears to stimulate key brain regions related to craving and reward.
Researchers from Boston Children’s Hospital in Massachusetts found that a meal high in refined carbohydrates (as opposed to a low GI meal) not only increased hunger, but stimulated parts of the brain associated with addiction 4 hours after eating — a critical period of time that influences eating behaviour 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 for carbs
In the new study, participants tasted 2 milkshakes that had similar ingredients, calories (500 kcal), appearance, taste, and smell. They were not aware which was the low GI meal or which was the high GI meal and reported no preference for either milkshake.
The researchers carried out a blood glucose, neuroimaging and rated their hunger levels after 4 hours – a time when the group would be considering what to eat for their next meal.
After eating the high-GI shake, participants had an initial spike in blood glucose level that was 2.4-fold higher than after the low-GI shake, followed by a crash in blood glucose at 4 hours as well as experiencing strong hunger pangs.
Dr Ludwig stated “Every single subject showed intense activation in the nucleus accumbens, the area of the brain related to addiction.”
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 stated that the study must be repeated with a larger number of participants and in a more diverse population and that it should be carried out before and after weight gain.
However, he concluded that “Avoiding highly processed carbohydrates could help overweight people avoid overeating.”
Am J Clin Nutr. Published online June 26, 2013
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