A Big Fat Crisis (10 page)

We don’t do much better when it comes to beverages. When glasses had ice in them, even after training, people had difficulty estimating the amount of drink in the glass, unless the glass was full of ice. (In that case, the rule of thumb is that the liquid is about half of the glass’s volume.)

What about estimating the size of a pizza? How much bigger are the second and third pizzas compared to the first?

F
IGURE
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We usually estimate size based on one dimension
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Although most people know the formula for the area of a circle is πr
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, the calculation is neither easy nor automatic. So we don’t easily grasp that the medium pizza is twice the size of the smallest and the largest pizza is three times the size of the smallest. (The pizza sizes in the illustration, from left to right, are 50, 100, and 150 square inches.)

In some studies, training in judging portion sizes either doesn’t help or doesn’t last. When tested again several weeks later, people didn’t remember what they’d learned and made the same mistakes they’d made before. In one weight loss study of 177 people, most initially lost weight when they had meals with the correct portion sizes delivered to them for eighteen months.
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Although they had a better understanding of portion sizes than participants whose meals weren’t delivered, they ended up regaining the weight they had lost and ultimately fared no better than those without the portion training and meal delivery.

Variety Makes Us Eat More

Although portion sizes influence how much we eat, so does the variety of food available. Professor Barbara Rolls prepared three types of
pasta—spaghetti, bowties, and macaroni—and studied how much subjects consumed when offered pasta of one shape compared to being offered all three shapes.
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Each serving was prepared to have exactly the same calories and the same ingredients, so the only difference was the shape of the noodle. One group was offered three courses of spaghetti, a second group was offered three courses of bowtie noodles, a third group was offered three courses of macaroni, and a fourth group was given a different shape for each of the three courses (spaghetti, followed by bowties, followed by macaroni).

It turned out that just changing the shape of the pasta increased participants’ appetites! They ate 14 percent more when offered three different shapes of pasta compared to one. And of course, the participants in the study had no idea how much they were eating, that the different shapes of the food encouraged them to eat more, or that getting only one shape made them eat less.

The same type of experiment has since been repeated with different kinds of foods and different groups of participants, all with the same result: when people have more variety, they eat more.
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To better understand how variety stimulates more eating, scientists have asked participants to rate food every minute they eat. As people continue to eat the same food and they get full, the sense that the food is pleasant decreases. The pleasantness of a food starts to decline within the first five minutes of eating. This is called “sensory-specific satiety.”
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However, when a different food is offered, pleasantness ratings increase for the new food. If the food differs only in flavor or appearance, people may eat only slightly more, like the 14 percent increase in the pasta study. If the food has a different texture, content, and flavor, increases in consumption have been up to 40 percent.
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The Role of Repetition and Novelty

Remember that knock-knock joke where the answer to “Who’s there?” is “Banana,” not once but at least a dozen times? Finally, the answer to “Who’s there?” becomes “Orange.” “Orange who?” “Orange you glad I didn’t say banana again?”

The joke is an example of how people respond to boring repetition,
which can apply to food as well. We would get very tired of having even the most delicious meal over and over again. When something different comes along, we’re grateful for the novelty. Variety not only affects our ratings of foods’ pleasantness; it also increases how much we salivate.
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In one study, children between the ages of nine and twelve had cotton balls placed in their mouths to measure their saliva. Then, for one minute, half of a fresh Wendy’s cheeseburger was placed on a table one inch from each child’s mouth, at the height of his or her lower lip. The children were asked to look at the burger, smell the burger, and think about eating the burger, but they were told they could not eat the burger. After one minute the researchers took the burger away, took out the cotton balls, and gave the kids a one-minute break. Then they put in new cotton balls; placed the burger one inch from the children’s mouths again; and asked them to look at it, smell it, and think about eating it, but not to touch it. Again, after one minute the researchers removed the food and took out the cotton balls. They repeated this procedure seven times to measure the amount of saliva the cotton rolls absorbed. For the eighth time, half the group was presented with a portion of Wendy’s french fries while the other half once again had to look, smell, and think about the cheeseburger. With each of the first seven trials, the amount of salivation decreased substantially. However, in the last trial, salivation among the group shown the french fries skyrocketed to reach almost the same level measured the first time they saw the cheeseburger.
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Sensory-specific satiety, getting tired of the taste of a particular food, occurs not only because one’s stomach is full but also because of habituation, which means we get so used to something that we begin to register a response sooner than we did previously, resulting in eating less. Sensory-specific satiety can develop when people simply smell a food, or chew the food over and over without swallowing.
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In one study, participants were asked to drink as much orange juice or coffee as they wanted, until they felt full. However, half the group was first asked to rinse their mouths with the drink and not swallow it. Those who did the rinsing procedure drank less than those who did not—so
sensory-specific satiety occurs whether or not we actually eat the food. Eating the same old thing quickly reduces our motivation to continue eating. Variety delays satiation and encourages and prepares our body in many ways to continue to accept and crave food.

The attraction to food variety affects all people. In one intensive experiment, six lean and six overweight men were asked to stay in a residential laboratory for nine days.
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During this time they were given access to five types of food (considered a low level of variety), ten types of food (a medium level of variety), or fifteen types of food (a high level of variety). All the men ate more calories when they had access to the high variety of foods. The lean men gained weight when they had a high variety of foods. The overweight men lost the most weight with the lowest variety of foods. Similarly, soldiers given “meal, ready-to-eat” (MRE) rations tend to lose weight, partly because of the monotony of eating the same foods day after day.
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The food industry is very aware of people’s attraction to variety, and as a consequence it introduces more than ten thousand new processed food products annually into US markets.
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These foods tend to be high in sugar and fat, so they pack a double punch, exploiting not only our natural attraction to novelty and variety but also our preferences for these energy-dense ingredients. Picture the cookie aisle in the supermarket—how many varieties of Oreos are there? The Oreo website shows forty-seven different products. You can get chocolate-covered Oreos, Oreos with purple creme, Oreos in mini sizes, or Oreos stuffed with double creme. You can even get Oreos made with organic flour and sugar.

How many different types of Pop-Tarts are in the cereal/breakfast aisle? I counted thirty-six on the manufacturer’s website, including Barbie Pop-Tarts, Vanilla Milkshake Pop-Tarts, and Pop-Tarts made with whole-grain wheat and brown sugar and cinnamon-toasted with icing.

The food variety in our environment is now so great that it may actually be turning normal-weight people into dieters. It’s likely that many of us find ourselves exhausted by the end of the day from just seeing all the variety and having to refuse, resist, or try to ignore it. Variety has positive consequences when it comes to fruits, vegetables,
and whole grains, because we get more nutrients with fewer calories. But eating too many foods that are high in sugar and fat may lead to chronic diseases.

Other People Can Make Us Unconsciously Eat More

Remember the game Simon Says? While demonstrating the moves, the leader shouts out the commands: “Simon says, Touch your face. . . . Simon says, Touch your nose. . . . Simon says, Touch your knees. . . . Simon says, Touch your shoulders.” Everyone has to do what Simon says. Players are eliminated if they mimic the leader when he doesn’t preface the command with “Simon says.” But the leader can also trick the players by doing different things than what he says. He might say, “Simon says touch your mouth” while touching his waist. It’s surprisingly easy to imitate the action rather than follow the verbal direction.

Our ability to move our bodies and copy what we see is much faster than our ability to hear what someone says, process the information, and then act on it. Mimicking is an automatic behavior like eating. In fact, it is a normal and important part of development and growth; children learn to talk by imitating the sounds they hear. We sometimes unknowingly copy the motions and movements that we see others perform—yawning, scratching, crossing arms, and leaning.
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So it should be no surprise that we automatically copy others’ eating behaviors as well.

Several studies have demonstrated that our tendency to automatically mimic others affects how much we eat. In an ice cream taste test, participants were paired with someone they thought was another study subject but who was actually a lab assistant instructed to behave in one of two ways.
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Half the time, the lab assistant was instructed to “spoon large quantities of ice cream into her bowl and eat rapidly and hungrily, with great enthusiasm.” For the other half, the assistant was told to “spoon small quantities of ice cream into her bowl and taste it delicately and slowly.” Participants were told not to pay attention to or wait for the other person to finish and that they could taste as much of the ice cream as they wanted and take as long as they needed to
complete the taste test. After rating the ice creams, they also had to estimate how much they had eaten and how much their tasting partner (the lab assistant) had eaten. The experimenters then weighed the remaining ice cream and calculated how much each participant had actually consumed.

When the lab assistant ate a large amount of ice cream, the participants also ate more—almost double the amount eaten when the lab assistant ate a small portion, and 50 percent more than when participants did not have a tasting partner.

When participants were asked how much ice cream they thought they’d consumed, they were actually quite good at judging. However, when asked how much they thought the lab assistant had eaten, they said they had no idea and vehemently denied paying attention to the other person. Moreover, none of the participants thought that the other person influenced how much they ate.

We mimic other people’s eating behaviors in many more situations than we realize. The more people there are at a dinner table, the more each person eats. For example, with two diners, each eats 33 percent more than if he or she ate alone; three diners typically eat 47 percent more; four, 58 percent more; and so on. With seven companions, people eat nearly double what they would have eaten alone.
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If we have finished eating and we see another person still eating, we may unconsciously mimic the other person and take another bite. With more people at the table, we stay longer and we eat more.

Our mimicking tendency goes beyond simple unconscious imitation—it can even change our preferences.
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In one experiment conducted at Duke University, 147 students were asked to participate in a study about advertisements and memory. However, the real purpose was to study mimicry and awareness of mimicry. Three days before the study, the students were asked to fill out a questionnaire regarding which snack they liked the best. At the time of the study, the students and the experimenter, who was shown on a videotape, both had two bowls of snacks in front of them: one filled with animal crackers and the other filled with goldfish snack crackers. The experimenter told the students they could help themselves to the snacks at any point. With half of the students, every ten to twenty seconds, the experimenter
would eat an animal cracker. With the remaining half, he would eat the goldfish. The researchers videotaped the students and later counted how much of each snack the participants ate. Afterward, the students were again asked to complete a questionnaire that included answering which snacks they liked best.