Anticipated Fullness Is Crucial to Calorie Intake
Experts have challenged two basic assumptions behind food choices and the causes of obesity.
Drs. Jeff Brunstrom and Peter Rogers of the University of Bristol, UK, investigated the theory that we eat larger amounts of tasty foods, and that these foods tend to be energy-dense.
They explain that highly palatable food is more widely available than ever before. This is one aspect of the so-called “obesogenic environment,” thought to contribute to rising levels of obesity. But they ask: does this necessarily lead to the selection of larger meals?
To answer the question, they carried out a study to measure ideal portion sizes of several popular and well-liked foods. Crucially, they also measured “expected satiation,” that is, to what degree each food would satisfy diners.
In the experiment, 28 normal-weight men and women assessed images of 16 foods at lunchtime, having not eaten for three hours. The foods were: fish fingers, pasta and tomato sauce, raw banana, crackers, chicken tikka masala, Jaffa cakes (chocolate covered sponge snack), pretzels, fries, Pringles, peanut M&M’s, cashew nuts, Crunchie bar (honeycomb covered in chocolate), KitKat, potato salad, chicken chow mein, and baguette with cheese.
Participants chose their ideal portion size for each food, as if they were eating only that food for lunch. They then selected an equally filling portion of a comparison food (pizza). Next they rated their anticipated liking for each of the foods, and reported how much money they would spend on a typical portion.
Results showed that foods with a high expected satiation tended to be selected in smaller portions (fewer calories). The actual energy density of a food was not linked to its ideal portion size. But high energy-dense foods were expected to be less filling per calorie than low energy-dense foods.
Surprisingly, better-liked foods were not chosen in greater quantities. The lack of a relationship between liking and ideal portion size is “particularly striking,” the researchers state.