Apples or apple juice. Food rheologists study different forms of foods and how the form of a food affects how full we feel when we eat it. One study prepared portions of apple juice and apples with the same number of calories. Half of the subjects were fed apples on one day followed by apple juice on a later day; the other half received the apple juice followed by the apples. After eating, the subjects were asked about how full they felt. Is this an experiment? Why or why not?