A Big Fat Crisis by Deborah Cohen Read Free Book Online Page A

smaller plates so that we will be more likely to put less food on our plates and thus eat less. Once again, this seemingly commonsense advice did not hold up to rigorous scrutiny. 3 To understand more about the potential role of plate size, Dr. Barbara Rolls, the Penn State researcher whose experiments on food variety and portion size were described earlier, invited participants to her lab to eat lunch once a week. Each week, she served the same foods but varied the size of the plate. Just as with the pizza example in Chapter 4 , the largest plate had more than double the surface area of the smallest plate. The participants were asked to help themselves either to one main course or to a buffet with five different food choices. The foods were weighed before they ate and the remaining amount was weighed when they finished, so it was possible to determine the quantity eaten.
    It turned out that the size of the meal consumed did not differ regardless of the size of the plate. The participants’ ratings of hunger and satiety did not differ by the size of the plate either. When the participants had only one main course to choose from, three-fourths of them didn’t even notice there had been a difference in the size of theplate. However, when the participants had to go back and forth to the buffet table to get food, most of them did notice the difference in the plate sizes.
    In a follow-up study, participants were given a set amount of food. The researchers then gave them plates seventeen, twenty-two, or twenty-five centimeters in diameter (about 6.5, 8.5, or 10 inches). In this condition, again, the size of the plate had no effect on how much they ate.
    Will Hundred-Calorie Packs Help?
    Portion size appears to be more important than plate size in determining how much people eat. When portion sizes are reduced, people eat less. Because of this the food industry has developed products like hundred-calorie packs. These are typically limited portions of snack foods—like chocolate chip cookies, crackers, chips, or other foods that have high levels of calories per gram. It makes sense that if we are served less, we will eat less. However, one study suggests that small snack bags might have a perverse effect and encourage people to eat more.
    Researchers invited people to a laboratory with the cover story that they wanted participants to watch television and rate some TV advertisements. 4 They told the participants they wanted to simulate the same conditions as in a typical home, so they left snacks in the room, telling them to feel free to help themselves, because a lot of people snack when they watch TV.
    For all the groups, the researchers measured how many chips they ate while watching and rating the TV advertisements. For half the participants, they provided five small bags of potato chips (forty-five grams); for the other half, they provided one big bag of potato chips, weighing two hundred grams. They also divided each of these groups in half. One group got no other instructions, but the second group was first primed to be concerned about their body image. Before being asked to watch the advertisements, they weighed the second group of participants, measured their waists, and had them look at themselves in the mirror.
    The results were unexpected. The group that was in the room with the small bags ended up eating more than the group with the single big bag. This was mainly because the people offered the small bags were more likely to open one, while just a small number opened the big bag. Of the individuals who opened any bag, the group that ate the least were those primed to worry about their body image and who had access to the big bag.
    It seems that when the participants were reminded about their weight, they were more likely to monitor themselves and limit what they consumed. In contrast, the group with the small bags may have felt that having the chips already measured out for them ensured that they would not be eating too