Calorie Intake Goes Up As Cereal Flake Size Goes Down

Barbara J. Rolls, PhD Department of Nutritional Sciences The Pennsylvania State University, 226 Henderson Building University Park, PA Interview with:
Barbara J. Rolls, PhD
Department of Nutritional Sciences
The Pennsylvania State University, 226 Henderson Building
University Park, PA 16802-6501 What are the main findings of the study?

Dr. Rolls:  We found that as we reduced the flake size of a breakfast cereal so that it filled a smaller volume, individuals ate a greater weight and more calories of the cereal. On four occasions, we served a popular wheat flake cereal, or the same weight of cereal crushed to 80%, 60%, or 40% of its volume, to 41 adults for breakfast. As the flake size was reduced, people made reductions in the volume of cereal they poured, but they still took a greater amount of weight and calories. They ended up eating 72 more calories at breakfast when they ate the cereal with the smallest flake size, an increase of 34%. These findings show that variations in food volume due to the size of individual food pieces affect the portion of food that people take, which in turn affects how much they eat. Were any of the findings unexpected?

Dr. Rolls:  People in the study tried to adjust for the more compact flakes by pouring a smaller volume, but they didn’t go far enough to select a portion with the same weight and calories. They ended up taking and eating more calories, even though they estimated that they were taking the same number each time. What should clinicians and consumers take away from your report?

Dr. Rolls:  People have a hard time judging appropriate portions. On top of that you have large variations in volume that are due to the physical characteristics of foods, such as the size of individual pieces and how things pile up in a bowl. That adds another dimension to the difficulty of knowing how much to take and eat.

Differences in food volume present a challenge not only to calorie balance but also to advice on recommended portion sizes. There are a lot of variations in food volume that we’re not given much advice about. Our research shows clearly that, without us even knowing it, these variations can have a big impact on how much we’re eating. What recommendations do you have for future research as a result of this study?

Dr. Rolls:  The effects seen here for cereal flake size are likely to extend to the many other foods. Further research is should examine foods with other properties that affect volume, such as degree of aeration, cooking, and variations in the shape of pieces.


Variations in Cereal Volume Affect the Amount Selected and Eaten for Breakfast
Barbara J. Rolls, Jennifer S. Meengs, Liane S. Roe

Journal of the Academy of Nutrition and Dietetics – 21 March 2014 (10.1016/j.jand.2014.01.014)


Last Updated on March 28, 2014 by Marie Benz MD FAAD