Drugs, alcohol, nicotine ... processed carbohydrates? Dr. David Ludwig of Boston Children's Hospital says certain carbs affect our brains, much like addictive substances.

Guests:

• Dr. David Ludwig of Boston Children's Hospital, Professor of Pediatrics at the Harvard Medical School and a Professor of Nutrition at the Harvard School of Public Health.

When we think of addiction, a few key substances probably come to mind, including drugs, alcohol, and nicotine. But carbs? While there probably won't be an AMC drama about french fry dealers any time soon, a recent study from Dr. David Ludwig of the Boston Children's Hospital suggests that processed carbohydrates may have more addictive properties than we previously realized.

We know indulging in that giant piece of strawberry cheesecake can make us feel slow and sluggish, but how does it affect our bodies from the inside? Most unprocessed foods like fruits take a long time to digest, so blood sugar stays stable and insulin levels rise only slightly after you eat them. After eating highly processed foods, however, blood sugar skyrockets and then plummets, meaning these foods have what is known as a "high glycemic index."

In Ludwig's study, participants ate different kinds of milkshakes - identical in color, taste, and texture - except one had a high glycemic index, and the other a low. After the milkshake with a high glycemic index was ingested, blood sugar rapidly rose and then collapsed, just as expected. What was interesting was how this process played out within the brain itself. Four hours after eating, when blood sugar dropped, brain scans of the subjects showed intense activation in nucleus accumbens, the brain's "ground zero" of pleasure, reward, craving, and addiction. Junk food, it turns out, activated the same part of the brain as other addictive substances like drugs and alcohol.

How does this study change the way we look at obesity? Traditionally, society has viewed obesity as a question of will power - that many people could just lose that extra weight if they really wanted. But, as Ludwig counters: "If it was simply an issue of will power, frankly, I wouldn't have any patients." Indeed, this study turns that view on its head, by suggesting that processed carbohydrates provoke a reaction in our brain that makes our bodies want them more - in other words, they make it even more difficult for us to eat well. However, that also makes the inverse true, as Ludwig notes: “By choosing the right foods, it can make remaining on a healthful diet easier," he says.

To hear more about which foods to eat as alternatives and how Dr. Ludwig changed his own lifestyle after beginning to study processed carbs, tune in to our full interview above.