What Drives People to Overeat

DECEMBER 01, 2008
Guido Zanni, PhD

Dr. Zanni is a psychologist and health systems specialist based in Alexandria, Virginia.

Twenty years ago, few psychologists studied eating behaviors, but interest in food psychology has expanded with America's waistline. Some of the most interesting findings are featured in Mindless Eating, a book by Brian Wansink, PhD. Dr. Wansink conducts research on eating behaviors at his Cornell University laboratory, which resembles a restaurant, a cafeteria, and a television den, and simulates environmental, social, and cognitive variables.

Consider this environmental cue: serving bowl size. Participants serving themselves from either gallon-size bowls or half-gallon-size bowls ate 59% more snacks from the larger bowl.

And cognitive expectations? While eating identical meals, subjects received a complimentary bottle of wine from either Noah's Winery, California, or Noah's Winery, North Dakota. The bottles contained the identical inexpensive wine. Those with the California label ate 11% more food, lingered an extra 11 minutes, and rated the food and wine higher in quality, compared with those receiving the North Dakota label. The participants' belief that California wines are better affected their entire meal (known as the halo effect). Similarly, people will order Belgian Black Forest Double Chocolate Cake with greater frequency and rate it higher than the same menu item simply called Chocolate Cake.

How strong are cognitive expectations? In one study, approximately 60% of participants in a darkened room who were given chocolate yogurt, but told it was strawberry, rated it as having a good strawberry taste.

Final Thought

Knowledge is not power in this area. Subjects who attended a 90-minute lecture on food psychology still fell victim to cues. Food psychology helps identify cues and thoughts fueling overeating— cues that clinicians might use to a dieter's advantage.

Did You Know?

  • Individuals are aware of only 20 of their daily average of 200 food decisions.
  • The more people like the food, the faster they eat.
  • Individuals eat 28% more popcorn during sad movies than happy movies.
  • Females prefer ice cream, chocolate, cookies, and other snacks as comfort food; males prefer ice cream, soup, pizza, or pasta.
  • More comfort foods are consumed when happy than when bored, lonely, or depressed.
  • Individuals pour and drink 25% to 30% more when given a short, wide 22-ounce glass, compared with a tall, thin 22-ounce glass.
  • The larger the package, the more people eat: 23% more spaghetti, 48% more candy, 53% more popcorn. The same occurs with healthy foods.
  • The longer people watch television, the more they eat.
  • Less is eaten on hot days and more on cold and rainy days.
  • Individuals eat 35% more food when eating with others, with one notable exception; overweight people eat less when eating with thin diners.
  • Inconvenience decreases consumption. Placing candy 6 feet away led participants to eat approximately 50% less than when the candy was on their desks. In cafeterias, people eat less if they have to purchase chips or candy at a separate counter.
  • Real or perceived variety increases consumption. Subjects who sampled 6 candies mixed together consumed almost 50% more than subjects who sampled 6 single flavors separated into 6 bowls.
  • People consume less when given consumption cues. Participants ate 28% fewer chicken wings when the bones were left on the table than those whose server periodically removed the evidence.