WebMD Health News
Nora Volkow, MD, is director of the National Institute on Drug Abuse. She was a featured speaker at the 2014 TEDMED Conference, where she talked about the role of addiction in obesity. She answered some questions for WebMD after her talk.
Q: Is it possible to be addicted to food? And are some foods more addictive than others?
A: I used to use that term much more easily in the past, but I think people react very negatively about the concept of addiction to food, because it leads to misunderstanding.
Clearly, there are foods that are much more likely to trigger that loss of control and compulsive overeating that resembles what you see in people addicted to drugs. These are foods that are very rich in fat, sugar, or salt. And these are the foods that can, if you get exposed frequently and repeatedly, can produce compulsive overeating—the ones where you can’t just “eat only one.”
These are the foods where even if you’re full, you can’t resist them. Then you end up overeating and overeating and overeating, and that then eventually leads to obesity.
That would never happen with something like a tomato. You’ll never feel a compulsive need to eat more and more and more tomatoes.
Q: Well, shoot. We were just going to ask if it was possible to become addicted to broccoli.
A: No, I don’t think so. It doesn’t have the chemical characteristics needed for addiction.
You can actually emulate these very nicely in lab experiments with animals. You can provide a rat with pellets that are very high in fat, and you will see that they compulsively eat them, and you can see that they’ll consume more calories within an hour than they would normally eat for 2 days. And that’s the nature of the food, not the rat. That’s the nature of the food we get exposed (to), not ourselves as humans, who should be blamed.
Q: What other foods encourage overeating?
A: Sugar is probably the one that’s been the most investigated. It directly increases dopamine in your brain. [Editor’s note: Dopamine is a chemical that’s involved in the brain’s reward system.] Even if you don’t taste it, you don’t need to taste it. Having sugar in your blood plasma will release dopamine in the brain’s reward regions. That’s why it’s such a potent reward and why we get conditioned to sugar.
Q: If foods can be addicting, does that suggest that we need a different approach to the treatment of obesity?
A: We really need to think about obesity in terms of the importance of mounting prevention strategies that actually are going to protect us from the adverse effects of being surrounded by very, very highly rewarding food, which is everywhere.
We need to re-engineer the environment. If we really want to address the problem of obesity, we should do what we’ve done with tobacco smoking, except at a much more aggressive level, because we can’t afford to have 30 years to reverse the obesity epidemic. We should re-engineer environments within a 10-year period, so really we’re not promoting the compulsive eating of very, very obesogenic food.
Q: The newly-approved weight loss drug, Contrave, combines two medications that are used to treat addictions: bupropion, which is used in the anti-smoking medication Zyban, and naltrexone, which is used to treat opioid addictions. Is blocking an addiction to certain foods part of how Contrave works?
A: These drugs, both bupropion and naltrexone, are involved both with the rewarding and conditioning responses to drugs in the brain.
Specifically, naltrexone is a new opioid antagonist. … The hedonic component of eating certain foods, which is the capacity to perceive the pleasure from them, is blocked by naltrexone.
Bupropion, on the other hand, directly targets the dopaminergic systems that are linked to condition responses that enhance motivation.
When you see, for example, something that you’ve associated with a reward — like chocolate, or the smell of a donut — those are potent conditioned responses that are mediated through dopaminergic pathways that are disrupted in obesity. The higher your body mass index, the worse the function of these dopaminergic pathways.
The bupropion … will enable you, on the one hand, to help you control better these conditioned responses. Dopamine also regulates areas in the brain involved in self-control. That’s very much disrupted in addiction and obesity .
So yes, the Contrave is targeting these behaviors that are linked to the very rewarding effects that certain foods can have in our brain that can result in compulsive overeating.