How to stop eating chips
Photo: Sonja Lekovic/iStock/Thinkstock
You want to exercise more. But rain, fatigue, looming deadlines, and bad sneakers (that's right—blame the sneakers) get in your way. What is really going on? Why do dieters falter and armchair athletes remain seated? Turns out it's not about "weakness." (We can all stop beating up on ourselves right now!) And what we're learning about the brain points to new strategies that will really—finally!—make all the difference.

Nora Volkow wants my chocolate. I'm sitting at a round conference table in her large-windowed office at the National Institute on Drug Abuse, where she's the director. Volkow is telling me about her research into the neurology of eating and how, for some people, quitting foods—like, say, chocolate—can be as hard as kicking heroin is for a junkie. Food, she says, hooks people by triggering the exact chemical reactions triggered in the brain by hard drugs. Or nicotine.

Or alcohol. Or shopping. Or sex.

"I can't stop looking at your chocolate," Volkow says, her eyes darting from me to the chocolate and back. It's a Hershey's Kiss Volkow's secretary gave me moments earlier. I took it with a smile and a thank you, but I'm one of the few women in the world who actually don't like chocolate. So I bit off the tip to be polite, put the rest back in its metallic wrapper, and slid it onto the table next to my notebook. This makes Volkow uncomfortable, which isn't what I expected.

Most articles about Volkow focus on her childhood in Mexico City. They say, "Isn't it amazing she was raised in the same house where Stalin had her great-grandfather—Leon Trotsky, the exiled Russian revolutionary—murdered with an ice ax?" They talk about how Volkow started medical school at 18, then went to the United States and became one of the nation's leading research psychiatrists. But to me, the most fascinating thing about Volkow is the fact that she—the head of the country's national drug abuse agency—is not just a chocolate junkie. She's also a chocolate pusher. Volkow paces back and forth in her Bethesda, Maryland, office—frizzy hair bouncing, black knee-high boots clacking—then stops, narrows her eyes, and grins. "I have some good stuff," she says, reaching into her desk drawer. "Seventy-seven percent pure cocoa." She throws a quarter-eaten bar on the table next to me. "Go ahead," she says, "have some." I tell her no thanks, and she raises her eyebrows.

"I do experiments with people," she says. "I put the chocolate there and see how long it takes them to pick it up." She shakes her head. "I am very bad with chocolate. I take it immediately. I fail my own test. But you," she says, pointing at my Kiss, "you have very good inhibitory control!" This makes me laugh, because if she'd offered cheesecake or Swedish Fish, I wouldn't have lasted five seconds.

But my problem isn't food; it's exercise and the fact that I seem incapable of doing it. No matter how many times I join a gym or buy new workout clothes or make workout dates with friends, I simply don't exercise. I've always got good reasons: I'm too busy, it's raining, I need better shoes, there's no gym in my neighborhood. I have a deadline, a headache, or cramps; it's too hot or too cold, running hurts my feet, weights are heavy...I could go on. The rational part of my brain knows I should exercise: I've read articles saying it prevents nearly every human disease, fights depression, and strengthens the immune system. I hear it reduces stress and anxiety, that it helps you focus and sleep and have better sex. I want all that—who doesn't? But apparently, another part of my brain—which happens to be the dominant part—wants everything to stay exactly as it is.

And clearly, I'm not alone. At this point, it's common knowledge that the leading causes of death in the United States—heart disease, diabetes, and some cancers—are largely preventable through behavior change. Hundreds of thousands of people wake up each January 1 and say, "Starting today, I'm going to diet/exercise/quit smoking/taking drugs/gambling/whatever." They try, often very hard, but most fail.
Woman eating carrot
Photo: Hugh Kretschmer
I want to know why. And I'm not talking about external factors, like too much work and not enough time. I'm looking for what happens in our brains when we try to change, and how we can use that knowledge to actually succeed.

This is how I end up in Nora Volkow's office listening to her obsess about my chocolate. Volkow and colleagues have spent the past 15 years researching the link between drug abuse and obesity by studying one thing that makes it so freakin' hard to change a habit: dopamine, a chemical in the brain that transmits signals from cell to cell and gets us hooked on everything from food to cigarettes to shopping to sex.

Dopamine teaches your brain what you want, then drives you to get it, regardless of what's good for you. It does this in two steps. First you experience something that gives you pleasure (say, McDonald's french fries), which causes a dopamine surge. Some of that dopamine travels to the area of your brain where memories are formed and creates a memory connecting those fries with getting a reward. At that point, in sciencespeak, the fries have become "salient." And when you're exposed to something that's salient, you may think, "That's bad for me, I shouldn't,"  but your brain registers, "Dopamine jackpot!"

Which is where step two comes in: On top of creating memories, dopamine controls the areas of the brain responsible for desire, decision-making, and motivation. So once fries become salient, the next time you see or smell them, your brain releases a surge of dopamine that drives you to get more fries. When you succeed, your brain produces more dopamine, which reinforces the memory that made fries salient in the first place, etching it further into your brain. It's a never-ending cycle: The more you do something that's rewarding, the more dopamine makes sure you do it again. This is precisely how habits form. Eventually, if the fries become salient enough, your brain will release dopamine and push you to get fries anytime you see the colors yellow and red, even if you're nowhere near McDonald's.

And this is true for any behavior that results in a reward: Orgasms cause dopamine surges. So does hitting the jackpot when you gamble, winning a race, acing a test, doing cocaine or methamphetamines, smoking, drinking. "Dopamine is motivation," Volkow tells me. "If you create animals in the lab that don't have dopamine, they have no drive. They can eat food and it tastes good, but they have no motivation to actually do anything, so they won't eat, and they'll die."

As she's talking, I nod and take notes until, suddenly, her computer dings: She's got an e-mail. I am not compulsive when it comes to food, but e-mail? Forget it. Volkow doesn't share my obsession. She keeps talking about dopamine, I go back to taking notes, then there's that ding again, and I think, "She has two new e-mails." Volkow is unfazed. We go on like this until she must have 10 messages and I can barely resist getting up and reading them myself. Then it hits me: E-mail is as salient for me as chocolate is for Volkow. I often work months, sometimes years before seeing my books or articles in print, but e-mail gives me the reward of instant gratification. I tell Volkow this and she laughs. "You're right," she says. "I bet if I put you in an MRI machine and played that e-mail noise, you'd get the same dopamine surges I see in cocaine addicts when they think someone else is getting high."

This is why it's so hard to change. Doing so means fighting one of the most fundamental neurological systems in the brain. "Think about it," Volkow says. "If you're designing a species and you want to make sure it does things that are crucial for survival—like eating and reproducing—you create a system that's all about pleasure so they want to repeat those things. Then you have dopamine make those behaviors become automatic. It's brilliant, really."

Although she hasn't proved it yet, Volkow has a theory about why diets often fail: Based on animal studies, she thinks people may experience withdrawal when they try to kick certain foods their brains have become dependent on. "This makes it hard for them to eliminate those foods," she tells me, "because they may feel depressed or sluggish or generally horrible." If this turns out to be the case, she says, perhaps changing your diet more slowly will help.

But my big question for Volkow is this: How do you get yourself hooked on something that's not inherently pleasurable to you—like living on salads and broccoli or, in my case, exercising? Many people get a natural high from working out. I, however, am not one of them. "Isn't there some way to trick the dopamine system?" I ask her. "Some way to fool my brain into craving exercise?"

Sure, she says: The secret is thinking up rewards. My payoff for working out could be a pedicure or a new pair of shoes. For someone trying to diet: Maybe you get a massage after a week of good eating, or have a friend dole out gift certificates if you stay on track (you pay, but she controls the vouchers). "Giving yourself rewards for a behavior engages the dopamine system so your brain will associate the positive outcome with it, which will help you form the habit."

When I get home, I try it. I make a deal with myself: If I exercise every day for a week, I get a new mini MP3 player. I wake up in the morning and it's raining. I remind myself about the MP3 player. After several confused minutes of figuring out what a person wears to exercise in the rain (a poncho? an umbrella?), I end up in waterproof hiking boots and my boyfriend's hooded sweatshirt, which is three times my size. I leash the dog and we start running, but my boots are too heavy and my lungs burn, plus I can't see because the hood keeps falling over my eyes. And, of course, there's the rain. So we drop to a speed walk. An hour later we get home looking like we've been dunked in a river. I strip off my wet clothes and tell myself, "Do that six more times and you get an MP3 player." Then I think, "Yeah, right, you can't possibly exercise again without music." So I buy an MP3 player and tell myself I really need exercise clothes before I try something like running again.

The next day, I find myself in a very green and blue cafeteria at the Kennedy Krieger Institute in Baltimore, the renowned center for children and adolescents with developmental disabilities. I'm sitting across from Michael Schlund, PhD, a research psychologist who divides his time among several scientific institutions where he explores areas of the brain involved in learning and behavior change. For Schlund, this work is part of a larger project aimed at helping people with developmental disabilities, such as autism, learn. But what I'm interested in is a study he recently finished at the University of North Texas, where he spent months observing the brains of healthy adults as they learned new behaviors based on rewards.

Here's what happened: After sliding the volunteers into an MRI machine, he gave them two buttons—one for the right hand, one for the left—then said, "You'll have to make some decisions. If you're correct, you earn money. If you're wrong, no money." Then he fired up the machine, which rattled and clanged as it began scanning their brains. Inside the machine, on a computer screen above the volunteers' heads, a circle appeared and vanished. Next, the word CHOOSE flashed, which meant they had to pick a button, right or left. The game made no sense. There was no correct response: All they could do was click a button randomly, then the computer said WRONG and the circle appeared again. So they picked the other button and the computer flashed, CORRECT. YOU'VE EARNED 50 CENTS.

Once the volunteers knew which button to press in response to the circle, they repeated the process over and over. Circle. Correct button. Reward. Circle. Correct button. Reward. This is where it got interesting for Schlund, because he wants to know what happens in the brain when you learn a new behavior based on rewards, which parts light up, how big that activation is, and how it changes over time as the behavior becomes habitual.

On the first click, when they were guessing, the volunteers' brains lit up a little in the frontal lobe—an area associated with self-control, decision making, and behavior change. After the second click, when they got the reward for answering correctly, suddenly their brains kicked into high gear, and with each repetition, their frontal lobes lit up more and more, which meant their brain activity continued to increase as they learned the new behavior. But—and this is the good news—within about 50 repetitions, Schlund says, the reverse will start happening—the frontal lobe lights up less and less until the brain is exerting minimum effort, which means the new task has officially become a habit.

When Schlund tells me this, I ask if it means I only have to force myself to exercise 50 times and then it will be a habit. "I wish I could say yes," he answers. "But we really have no idea. What I can tell you is, there are many variables." The biggest one is stress. It turns out that the hormones released by the body in response to stress are our worst enemy when it comes to changing: They actually inhibit the frontal lobe, which makes the brain revert to behaviors that don't require conscious decisions (eating our familiar foods, drinking, smoking). Not only do stress hormones impair the areas of our brains that need to be active to change, they also stimulate our emotional centers, which send out signals telling us to decrease the stress. And what decreases stress? Food (because it triggers the release of natural opiates), alcohol, and cigarettes.

So successful change depends in part on stress management. But, Schlund says, it also depends on finding the right rewards. "If people got paid to exercise," he tells me, "everyone would do it. And this country would be much better off."

I ask if he'll pay me to exercise. He folds his hands on the Formica table between us, looks me in the eye, and says, "If you want to convince your brain you should exercise, you have to treat yourself the way you'd treat your dog." It's hardly the answer I'm looking for, but at this point, I'm open to anything.

"Imagine she's wetting on the floor every day," he says. "Are you going to say, 'Hey dog, if you don't wet on the floor for a week, I'll buy you a rawhide bone'? That would be like your boss saying, 'If you work five years, then you'll get your check.' It's too far off."

Obviously, this is why my MP3 player failed: A week was too long to wait. If I'm going to associate exercise with a positive payoff, the reward has to be immediate. But beyond that, Schlund tells me, I have to unlearn the rewards I've already associated with not exercising (no pain, more time for other things). Doing this actually requires changing my neural circuitry. And rewiring an adult brain, I am about to discover, is very tricky.

A few days into my meeting with Schlund, I'm sitting at a small desk in a psychiatric ward at Yale, staring at a computer screen with two clickable buttons: CHE and SHE. The computer says "che" (or is it "she"?), and I'm supposed to press the appropriate button. I click CHE. The computer buzzes and tells me to try again. "Che" or "she"? I click SHE. Buzz. Over and over, I get the buzz. I'm thinking this must be a joke, but then I squint, listen hard, and finally hear it. I hit CHE. The computer dings, then two pink kissing fish appear on the screen and do a funky dance with a hermit crab. That's my reward, which clearly gets my dopamine going: I start playing compulsively, completely hooked on picking the right answer so I can see what my next goofy reward will be. After a while, my attention starts wandering... buzz. So I squint, listen hard, and hear it again: "che." A spaghetti-thin man suddenly appears on the computer screen playing a xylophone, until a musical note hits him on the head. Then Bruce Wexler, MD, walks in the room.

Wexler, a leading neuroscientist and the author of Brain and Culture, studies brain plasticity and how it affects our ability to change. I've come to try out this program, which he uses to help patients with schizophrenia improve their audio processing and memory. "You're very good at that," Wexler tells me. Not really, I say, pointing out how many errors I made before figuring it out. But actually, that's the whole idea of the program: Successful change requires abnormally intense, uninterrupted concentration and repetition. Why? Because we're working against evolution: Our brains are designed to conserve energy for really important things, like breathing and coordinated motion, even though sometimes, altering behavior is just as important as breathing. Our brains revert to habits when given the chance because they require less energy than change. That silly exercise with "che" and "she" actually changes the way adults hear because it doesn't let that happen. It forces intense concentration resulting in instant rewards that make you want to repeat the exercise over and over again.

"You want to know why it's hard to change?" Wexler asked when I first walked into his office. "There are a hundred billion neurons in your brain. Each one is connected to thousands of others. Everything you're talking about—behaviors and learning and memory—involves the integrated actions of hundreds of thousands of cells in intricate systems throughout the brain." In adults those systems are essentially hardwired.

When you're a kid, it's a different story: Young brains are constantly forming new connections between neurons, changing the way children process information based on their experiences. That's plasticity, and it's why children soak up language and adapt to new cultures at rates that put adults to shame. "By the time we hit our 20s," Wexler says, "our brains have lost most of their plasticity." But fortunately, they haven't lost all of it.

Imagine you've got one strong eye and one weak eye, he tells me. If you cover the good eye with a patch, so it gets no stimulus, the weak eye will get stronger. But the second you remove the patch, the strong eye kicks in again and the weak one gets weaker. The same is true of all pathways in the brain. Once established, they stick around and remain strong as long as they're being used. So the first step toward change, Wexler says, is putting a "patch" over the pathway you want to lose (like, say, a chocolate obsession), which means eliminating anything that activates it (having chocolate in the house, going places where you usually buy chocolate). This is why, for many people who try to quit drinking or smoking, it's impossible to have just one glass of wine or cigarette. It's why heroin and coke addicts must avoid places and people connected to their drug days.

For dieters, just walking into your regular grocery store can activate an old familiar food pathway and keep it alive. So successful weight loss is as much about lifestyle change as it is about what you eat: Shop at a new store; buy new brands of food; use a new set of plates; eat in another room, at a different time of day. All these things will help starve an old, unhealthy pathway so you can develop a new, healthy one. "The more drastically you restructure your habits," Wexler says, "the more the established pathway that you're trying to change is weakened."

But disabling the old pathway isn't everything. Searching your brain for an existing healthy pathway—even a tiny weak one—and then strengthening it can make things much easier. So Wexler tells me to find an "I like exercise" pathway. I tell him I don't think I have one. He doesn't buy it. "Wasn't there some activity you loved as a kid?" he asks. I don't think so.

On the train ride home, however, as I stare out the window listening to my new MP3 player, David Bowie's "Changes" comes on and I start laughing. Appropriate, yes. But it was also the song my next-door neighbor and I skated to in my backyard when I was a girl. For my entire young life, I was obsessed with roller-skating. My first kiss was on skates; I roller-skated to high school every day, then rolled down the hall from class to class. I actually convinced my high school to waive my PE requirement and give me credit for my constant skating. Sitting on the train remembering all this, I smile and think, "I just hit my dopamine jackpot."

When I get home, I strap on my 10-year-old Rollerblades and give it a try. I turn on some disco and start rolling. It's sunny; my dog is running next to me. I can practically feel the dopamine coursing through my veins. My exercise problem is solved. Life couldn't be better.

The next day I wake up, walk into my living room, then sit down at my computer thinking, "Oh my God, I have so much to do." A few hours later I think, "I should go Rollerblade now." But I'm busy. I've got a deadline, I exercised yesterday, and besides, it looks like it's going to rain. I'll do it later. But when later comes, I'm tired from working all day, and now it's getting dark. Then I think, "Wait a minute. Why isn't all that dopamine from yesterday driving me to get up and Rollerblade again? Did my brain forget?"

A week later, I call Monika Fleshner, PhD, a neuroimmunophysiologist at the University of Colorado at Boulder who has done extensive research into the physiology of exercise. I explain my situation. I say I found an exercise I like, and I think I've got the dopamine thing solved, but funny thing is: I'm still not doing it.

You know what her bottom line is? Suck it up—just make yourself exercise.

Fleshner is very clear: It's not like you find your dopamine jackpot and your brain immediately says, "Now we exercise every day." For a while, you still have to force yourself to do it. But, I tell her, I have a very good reason not to: I know her research found that in animals, forced exercise doesn't lead to the same physiologic benefits that voluntary exercise does. In fact, it actually weakens the animals' immune systems by causing an increase in stress hormones in the body. I ask her about this, and she says it's true, but I don't have to worry about that. Why? Because I won't have to make myself exercise long enough to cause problems. To which I say, "Excuse me?"

Then she tells me something wonderful: All I have to do is force myself to exercise regularly for about two weeks, maybe three, and my brain will start producing a protein called brain-derived neurotrophic factor (BDNF), which she calls Miracle-Gro for the brain. It increases brain plasticity, so you can think clearly and focus for longer periods of time. It also increases dopamine neurotransmission, which means the more I exercise, the more reward I get, and the more my dopamine system is activated to make exercising a habit I'll soon crave.

"Just put on your Rollerblades," Fleshner tells me. "Strap on some headphones, leash up your dog, go outside, and start exercising right now."

Long, silent pause.

"I'm serious," she says.

I sit there holding the phone for a second before thinking, "Oh, what the hell. Three weeks isn't that bad." So I head out for day one. And yes, it's day one again, because I didn't go out for day two last time, which means I'm starting from scratch.

When I began this quest to find out why it's so hard to change unhealthy behaviors, I talked with more than a dozen scientists. Each one laughed and said some version of this: "If I could answer that question, I'd win a Nobel Prize and have drug companies lining up at my door for miles."

But the truth is, scientists have uncovered some very important things. To begin with, change is monumentally difficult. Some people can just wake up one morning, decide to change, and stick with it. But many, perhaps most, can't. The reason may be genetic; it may be the way you were raised; perhaps some people have stronger frontal lobes than others. Scientists still aren't sure. What they do know is, if you're one of those people who struggle, that's nothing to beat yourself up over—it's just the way your brain works. But it's also not an excuse to toss in the towel and say, "Well, I don't have enough dopamine" or "My bad pathways are too strong." As Bruce Wexler told me, "The more we understand what we're up against, the more we can develop strategies that will help us work with our brains to change successfully."

So instead of waking up New Year's morning and saying, "I'm going to do X now," then berating yourself a month later when that resolution didn't work, remember: You're doing nothing less than rewiring your brain. Approach change as if you're learning a new language or a new instrument. Obviously, you're not going to be fluent or play symphonies instantly; you'll need constant focus and practice. Overcoming an unhealthy habit involves changing the behaviors associated with it and managing stress, because stressing about change (or anything else) will knock you off the wagon faster than you realize. Above all, get that dopamine system going: Find rewards—make them instant, and don't be stingy. Your brain needs them. And I promise (well, Volkow, Schlund, Wexler, and Fleshner promise) it gets easier. That's not a bunch of self-help nonsense. It's biology.

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