Dr. David Ludwig, director of the New Balance Foundation Obesity Center at Boston Children's Hospital, and colleagues at Ulm University in Germany, the Beth Israel Deaconess Medical Center in Boston, Brigham and Women's Hospital in Boston and Harvard Medical School examined effects of the glycemic index on brain activity after an interval of several hours after eating.
Glycemic load accounts for how much carbohydrate is in the food and how much each gram of carbohydrate in the food raises blood glucose levels. It is based on the glycemic index -- the grams of available carbohydrate in the food times the food's glycemic load and divided by 100.
The study involved 12 overweight or obese men ages 18-35, who consumed high- and low-GI meals controlled for calories, macronutrients and palatability on two occasions -- two milk shakes, with the same amount of calories, protein, fat and carbohydrates that tasted equally sweet, but one with a much higher glycemic index from carbohydrates.
The study, published in The American Journal of Clinical Nutrition, found those who drank the milk shake with the higher glycemic index had their blood-sugar levels surge, then crash a few hours later, leaving them feeling hungry.
The brain scans showed the high glycemic milk shakes activated the nucleus accumbens, which is also triggered by drugs, which are addictive, the study found.