A psychologist dishes on what drives our diets
Many people are willing to give up chocolate for Lent or forgo drinking beer during pregnancy. But could you resist the temptation of sinful snack foods and calorie-rich beverages — and instead choose to eat only healthful foods — every single day for the rest of your life?
For most of us, the answer is no, but the reasons why you'd likely succumb to those Big Mac or Ben & Jerry's cravings may surprise you.
In this interview, behavioral psychologist Bradley Appelhans, PhD, of the Rush University Prevention Center, explains why people hunger for sugary, sweet and fatty foods, whether access affects our eating habits, and how to empower yourself to make smarter dietary decisions.
Q: Why is it so hard to resist eating junk food or to eat only small portions of certain foods?
Appelhans: Well, for a long time scientists thought that overeating and obesity occurred because people couldn't regulate their hunger and their satiety (the state where you feel full and satisfied). We now realize that obesity and eating behaviors are actually a result of the way our brains respond when faced with pleasures such as food.
The dopamine system, a neural pathway in the brain, is involved in the pathway in the brain known as the "reward circuit." Food reward includes both the pleasure we get from eating and the drive to consume tasty foods that are high in sugar, salt and unhealthy fats. It's the same reward you get from recreational drugs, sex, gambling or any other pleasurable activity.
This pathway, this reward circuit, is so powerful that it can override the natural mechanisms in your body that tell you to stop eating when you're full. That's why there's room for dessert even after a big meal. You wouldn't take another serving of broccoli or even pasta if you feel full, but you would take a slice of cake or a bowl of ice cream, just because it's pretty darn tasty and you want the reward from it.
Q: Is there any mechanism in our brains that helps to counteract the reward circuit?
Appelhans: That would be the prefrontal cortex. This is the area of the brain that controls our ability to suppress or inhibit urges to eat tasty foods. It's extremely difficult, though, for the prefrontal cortex to override the reward circuit.
The problem is that thousands of years of evolutionary history have led humans to the point where we actually prefer sweet, fatty foods in large quantities, and we've designed our food supply around these natural preferences. We are hunter-gatherers in our genes and our brains. Back when we were cave people, we needed to gorge on sugary, fatty foods help us survive periods of famine.
But those preferences were based on an environment where we hardly had anything to eat except animals, nuts, leaves and berries. Now, we have a whole league of scientists and food engineers who design processed, caloric, plentiful foods that perfectly fit our evolved preferences.
Unfortunately, we don't have sufficient systems in our brains to resist these urges; the prefrontal cortex is nowhere near up to the task compared to the reward circuit.
If you think of your brain as a sports car, the reward circuit is the gas pedal, but instead of regular brakes there's just an emergency brake: the prefrontal cortex. That's the only thing you have to try to slow the car down. And once you're driving 100 miles an hour, you really can't stop the car quickly or effectively using just the emergency brake.
Q: New York Mayor Michael Bloomberg tried — and failed — to pass a big soda ban, and the state of California is considering imposing a penny-an-ounce soda tax. Given how strong the reward circuit is, do you think making unhealthy foods and drinks harder to get would actually reduce people's consumption?
Appelhans: I certainly think that if you tax a food or restrict access, it can reduce consumption provided that the available alternatives are appealing. That's the rub, though.
For example, if you decide to impose a soda tax, you'd have to ensure that people aren't going to simply replace the soda with other calorie-packed beverages, like milkshakes, rich coffee drinks, sugary juices or sports drinks. Chances are, most people aren’t going to replace their soda with water or, say, freshly squeezed vegetable juice because those options aren't as tasty as soda.
If you're thinking in terms of reward, you have to make the alternatives appealing or rewarding enough that people won’t be motivated to simply find ways to get around whatever restrictions you’'e put in place.
Q: We hear a lot about "food deserts," and how people who live in these areas would eat healthier if only they had access to fresh, healthy foods like fruits and vegetables. Do you think that's true?
Appelhans: Is access really the main hurdle? You know, every day we're learning that it's a smaller and smaller part of the problem.
Years ago, researchers found all these associations where people living in food deserts were more likely to be overweight and get fatter and eat worse. But why do poor areas tend to have people who are heavier? There's a whole host of reasons, only one of which is access.
For example, many of the people who live in poor areas weren't middle-class folks who then became destitute: Most of them actually grew up in poor households where fresh food was scarce because it was less expensive to eat processed food or fast food or snack food from a convenience store.
For one of our recent studies, we gave participants vouchers to purchase groceries online through Peapod.com. And yes, people did order fruits and vegetables, but they also ordered plenty of sweet caloric beverages and snack foods.
So one important thing we learned from that study is that providing access by itself isn't going to have much of an effect unless we can also find ways to discourage folks from buying the unhealthy stuff. At least in this group of food desert households that we studied, they weren't using the free Peapod delivery just as a chance to finally get all the fresh fruits and vegetables that they lacked access to before.
Q: Are there any proven strategies that can help people make smarter choices?
Appelhans: Although we can't change our biology, we can make environmental changes that help the brain reduce overeating as opposed to simply trying to ignore or fight food cravings. You won't be able to control the entire environment that you live in, but you can at least control your own micro-environment: your home and, to a certain degree, your workplace.
The goal is to make the healthy choices the easy choices, and these strategies can help:
- Shop with a grocery list or use online grocers to reduce the urge to buy unhealthy foods in the store.
- Don't keep tasty foods in your home or office that you know will tempt you. It's OK to have ice cream, but don't buy a gallon of ice cream and stash it in your freezer; go to an ice cream shop once in awhile and buy a single ice cream cone.
- As often as possible, avoid dining in places where you're more likely to overeat and eat high-calorie foods, such as all-you-can-eat buffets and fast food restaurants.
Q: Is there a difference between the way kids and adults make food choices?
Appelhans: Absolutely, because when you're older, you can start to do things like weigh the future consequences of food intake, monitor your own behavior and delay your gratification. As a child and even a teenager, you don't think much about consequences and you definitely don’t want to delay that incredible feeling you get from eating something tasty.
It's all based on the development of the prefrontal cortex, actually. Before age 6, kids have a very primitive braking system. It gradually gets better, but the prefrontal cortex isn't fully developed until we reach our early 20s. So there aren't just behavioral differences between small children and adults, there are differences between teens and young adults and older adults.
Q: What can parents do to help their kids make better decisions about what to eat?
Appelhans: I would suggest transferring the decision-making about food to your child gradually, as you would with any other type of responsibility. Just as you wouldn't give a 5-year-old $1,000 to spend without a ton of direction, you shouldn't give kids unlimited access to junk food without any direction.
Finances are actually a pretty good parallel: You train kids gradually to take control of their finances. If you give kids no money and no chances to spend money until they're 18 or 21, you wouldn't expect them to suddenly be good at keeping track of their money when they start working, and they'll probably make bad decisions.
It's the same with food. If you deny your kids all sugary, fatty foods while they're growing up and they don't learn how to eat responsibly and manage what they eat, they'll have trouble when they're on their own and have to make their own choices. That's why parents and grandparents can — and should — play a big part in helping their kids get a healthy start in life.