Read the full article at the Chicago Tribune.

But what do we really know about how sugar affects us? Does eating sugar make us want to eat more of it?

First things first. Sugar is a carbohydrate, a category that includes starches. In addition to tasting sweet on your tongue, a spoonful of table sugar - in a cup of coffee, for example - will cause the sugar, or glucose, level in your blood to rise.

Your body responds differently to eating an apple, which is loaded with fruit sugars. For the same amount of carbohydrate, table sugar will prompt a much bigger spike in blood glucose than a few bites of apple.

That's because the apple's sugars are "in natural form, in the whole fruit," says David Ludwig, a physician and professor of nutrition at the Harvard T.H. Chan School of Public Health. "The sugar is sequestered in the structure of the fruit, and it leaches out slowly." In contrast, the sugar in sodas and candy, he says, "slams into the liver and raises blood glucose."

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."

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.

Highs and crashes and priming and wanting. That's the language of addiction. "Addictive substances usually have high potency and a rapid rate of absorption," Gearhardt says. Think snorting cocaine rather than chewing coca leaves. (The leaves contain minuscule amounts of cocaine, and chewing activates the drug's stimulant effects slowly.) Gearhardt says there's a parallel with foods that are highly processed and rapidly digested, "the foods that people struggle to eat in a manageable way."