Researchers at Penn State discovered that the size of flakes influences the amount of flakes people eat, and that the smaller the flake, the more flakes one will eat.
The research was published in the Journal of the Academy of Nutrition and Dietetics, according to FoodProductDesign.
The study found that when flakes were minimized by being crushed, people pour a smaller amount of cereal into their bowl, but still take a larger amount by weight and calories. The people eating the flakes still thought they were taking the same amount of calories.
"People have a really hard time judging appropriate portions," said Barbara Rolls, professor of nutritional sciences and Helen A. Guthrie Chair in Nutrition. "On top of that you have these huge variations in volume that are due to the physical characteristics of foods, such as the size of individual pieces, aeration and how things pile up in a bowl. That adds another dimension to the difficulty of knowing how much to take and eat."
Rolls said national dietary guidelines categorize recommended amounts of most good groups based on measures of volume, such as cups, Penn State News reported.
The researchers tested the influence of food volume on calorie intake by using a rolling pin to reduce breakfast cereal flake size so the same weight filled a smaller volume. Then, 41 adults were recruited and ate cereal for breakfast for four weeks, once a week. The cereal was either regular wheat flakes or crushed flakes with 80 percent, 60 percent, or 40 percent of the standard volume, FoodProductDesign reported.
The study showed that when flake size went down, participants poured a smaller volume of cereal but still took a larger amount by weight and calorie content, despite subjects guessing that they still took a similar amount of calories of all versions of the cereal, Penn State News reported.
Rolls said that the variations have a huge effect on how much people eat.
"For cereals with small pieces, the recommended serving size should be reduced to account for the uncharacteristically low volume, in the same way that the recommended serving size is increased for voluminous foods, such as puffed cereals and leafy greens," Rolls said.
