The Hungry Brain: Outsmarting the Instincts That Make Us Overeat

by Stephan Guyenet

needs. While this principle is sound, it also has a dark side: Food variety has a powerful influence on our calorie intake, and the more variety we encounter at a meal, the more we eat.

BEATING THE BUFFET EFFECT The fact that sensory-specific satiety drives us to overeat suggests a simple solution to the problem: Limit yourself to a few foods. If you find yourself at a buffet, tapas restaurant, or similar situation in which high food variety may cause you to overeat, simply choose three items you think would make a satisfying meal, and stick to them. You’ll probably feel just as full on fewer calories.

Sensory-specific satiety also helps explain why we’re happy to eat dessert even after a large meal. We’re no longer hungry for savory food at all, yet when the dessert menu appears, we suddenly grow a “second stomach.” We’re satiated of savory foods, but we aren’t satiated of sweets. A novel sensory stimulus with an extremely high reward value makes it easy to pack away an additional 200 Calories of dessert. So it makes sense that the converse is also true, as we saw with the potato diet: When food reward and variety decrease, so does food intake.

STEP AWAY FROM THE SNACKS The practical implications for avoiding overeating are clear: Don’t make it too easy for yourself to eat food throughout the day. Even effort barriers as small as having to open a cabinet, twist off a lid, peel an orange, or shell nuts can make the difference between eating the right amount and overeating. Keeping easy, tempting foods in plain sight, such as an open bag of chips or bowl of candy, creates a situation that is simply too tempting for the parts of our brains that are constantly on the lookout for a good deal.

we often make self-destructive choices, and this is particularly true when our decisions involve the future. As opposed to decisions that pit material objects against one another, like an apple versus an orange, we often make decisions that pit our present selves against our future selves. And the evidence shows that we often shortchange our future selves, with disastrous consequences.

On the bland diet, the starvation response never kicked in. Cabanac concluded that diet palatability influences the set point of the lipostat in humans.

High-reward foods tend to increase food intake and adiposity, while lower-reward foods tend to have the opposite effect. This suggests a weight management “secret” you’ll rarely find in a diet book: eat simple food.

It appears that exercise helps keep the lipostat happy at a lower set point.

EFFICIENTLY MANAGING OVEREATING One practical implication of this research is that if you want to control your weight over the long term, focusing on the six-week holiday period will give you the greatest return on your effort. Developing strategies to avoid holiday overeating, such as getting rid of holiday snacks in the kitchen and cooking lighter versions of traditional recipes, might go a long way toward curbing the inexorable upward arc of adiposity that most of us experience over our lifetimes.

Fruit, meat, and beans tended to have a high satiety index. Plain potatoes were off the charts—far more filling than any other food. Holt and colleagues noted that “simple ‘whole’ foods such as the fruits, potatoes, steak and fish were the most satiating of all foods tested.”

The more palatable a food, the less filling it was. Again, this makes sense. Palatable foods are those that the brain intuitively views as highly valuable, and the brain is quite good at removing barriers to their consumption.

Sticking with simple foods can help us restrain our calorie intake without feeling hungry.

A fourth critical factor that Holt’s team identified is fiber. The more fiber a food contained, the more filling it was. This

than white bread, despite their similar calorie density. Finally, the protein content of a food was a major contributor to satiety. This is consistent with a large body of research showing that protein is more filling than carbohydrate or fat, per unit calorie.

EATING FOR SATIETY If your goal is to eat fewer calories without going hungry, high-satiety foods will help. These are items that have some combination of low calorie density, moderate palatability, high protein, and/or high fiber, such as beans, lentils, fresh fruit, vegetables, potatoes and sweet potatoes, fresh meat and seafood, oatmeal, avocados, yogurt, and eggs. The exceptionally high satiety value of potatoes is undoubtedly one of the reasons why the “potato diet” we encountered in chapter 3 is effective. But if you cover your potato with calorie-dense flavorings such as butter and cheese, or deep-fry it into french fries, all bets are off.

whether a person is lean or fat in today’s world has less to do with willpower and gluttony and more to do with genetic roulette.

A century ago in the United States, people carried the same genes we do today, yet few people had obesity. What has changed isn’t our genes, it’s our environment—our food, our cars, our jobs. This leads us to a critical conclusion about obesity genes: In most cases, they don’t actually make us fat, they simply make us susceptible to a fattening environment.

“Genetics loads the gun, and environment pulls the trigger.”

“sleep restriction increases food intake. It’s as simple as that.”

For now, the best advice is probably to sleep as much as you need to feel fully restored, rather than following rigid sleep guidelines that are based on averages from population studies.

“When you have inadequate sleep,” explains Pardi, “you’re probably less likely to live in accordance with your own health goals. You’re less likely to get into bed on time, you’re less likely to go to the gym, and you’re less likely to have your eating behaviors align with your long-term health goals.”

In my view, the only realistic way out of this downward spiral is nationwide regulation that encourages a more slimming food environment while maintaining a level economic playing field for the food industry.

What do we care more about, the health of our nation’s children or our freedom to be bombarded by cheap, fattening food?

1. Fix your food environment Tempting food cues in your personal environment are powerful drivers of overeating due to their impact on brain areas that govern motivation and economic choice.

Reduce your exposure to food cues.

Manage your appetite If your brain thinks you’re starving, it will eventually wear you down, no matter how strong your resolve.

The most straightforward way to do this is to choose foods that send strong satiety signals to the brain stem but contain a moderate number of calories. These are foods that have a lower calorie density, higher protein and/or fiber content, and a moderate level of palatability. This tends to include simple foods that are closer to their natural state, such as fresh fruit, vegetables, potatoes, fresh meats, seafood, eggs, yogurt, whole grains, beans, and lentils.

Beware of food reward The brain values foods that contain calorie-dense combinations of fat, sugar, starch, protein, salt, and other elements, and it sets your motivation to eat those foods accordingly. This motivation is partially independent of hunger, such that it’s easy to blow past satiety signals if you’re eating something you love—think ice cream, brownies, french fries, chocolate, and bacon.

Make sleep a priority

Move your body Regular physical activity can help manage your appetite and weight in at least two ways. First, it increases the number of calories you use, making it less likely you’ll overeat. Studies show that when people with excess weight exercise regularly, their calorie intake tends to go up, but usually not enough to compensate for the calories they burn (although this does vary by individual). Second, physical activity may also help maintain the lipostat in the brain, encouraging a naturally lower level of adiposity in the long run.

Manage stress The threat response system evolved to protect us, but sometimes in the modern world it can undermine our quality of life and our best intentions to eat the right amount of food.

The first action is simply to identify whether or not you’re a stress eater.

The second action is to identify the stressor(s)—particularly chronic stressors you don’t feel you can control. These often include work stress, money, health problems, prolonged caregiving, interpersonal conflict, and/or a lack of social support.

The third action is to try to mitigate...

The fourth action is to replace stress eating with more constructive coping methods. Are there other enjoyable things you can substitute for comfort food when you’re stressed? How about calling a friend, making love, reading a good book, jogging, taking a hot bath, or gardening?

the fifth action is to remove calorie-dense comfort food from your personal surroundings at home and at work. In the absence of highly rewarding items, there’s less of an incentive to self-medicate your stress with food.