Q: Can sugar cause an addiction?

A: A spoonful of table sugar — in a cup of coffee, for example — will cause the glucose level in your blood to rise.

Your body responds differently to eating an apple, which is loaded with fruit sugars. That's because the apple's sugars are "in natural form, in the whole fruit," says David Ludwig, 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."

But the sugar in sodas or candy, he says, "slams into the liver and raises blood glucose." 

Scientists believe the rise in blood glucose is responsible for a craving.

"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."

Highs and crashes and priming and wanting. That's the language of addiction.

People may say they're addicted to sugar, and the addictive model may be useful for researchers as they study food cravings and overeating. But candy is not the same as heroin, says Larry Cheskin, director of the Johns Hopkins Weight Management Center. For people, eating and overeating are not only a result of physiological cues, he says.

If you stop eating foods with added sugar for a while, can you reduce your craving? Anecdotally, the answer seems to be yes. But there's been little research on this.

— Jill U. Adams, The Washington Post