This is what nutritionists are talking about when they cite a food’s glycemic index. A food with a high glycemic index raises blood glucose more than a food with a medium or low glycemic index. A rule of thumb is that the more processed, or refined, a food is, the higher its glycemic index, according the American Diabetes Association.
It’s not just sugary foods, either: White bread is a high glycemic index food, and potato chips fall in the medium category.
Scientists believe that the rise in blood glucose is responsible for the craving one feels for certain foods. “Sugary foods and refined carbohydrates cause a blood-sugar spike,” says Ashley Gearhardt, a psychologist at the University of Michigan. “And then three to four hours later, a blood-sugar crash. That cycle primes your brain and makes you want more of those foods.”
Ludwig imaged the brains of 12 overweight or obese men four hours after a high-glycemic-index snack and found increased activity in regions of the brain that respond to drugs of abuse.
Gearhardt asked 120 college students to identify foods that they “eat more and more of . . . to get the feeling I want, such as reduced negative emotions or increased pleasure.” Such language aimed to elicit foods eaten in an addictive way. Chocolate was No. 1, followed closely by ice cream, french fries, pizza, cookies, chips and cake.