Methods
Experimental design
This experiment used a crossover design with repeated measures within subjects. On one day a week for five weeks, participants consumed a mid-day meal consisting of a main course of pasta accompanied by a large portion of low-energy-dense salad.
Across the meals, the consumption of the salad was varied in two ways: whether it was served before the main course or together with the main course, and whether it was consumed in full (fixed intake) or consumed as desired (ad libitum intake). Specifically, at two meals the salad was served 20 min before the main course; one time subjects were instructed to consume the salad in full and once to consume it as desired. At two other meals the salad was served along with the main course; again, one was consumed in full and one was consumed as desired.
At the remaining meal, no salad was served. The pasta was eaten ad libitum at all meals. The order of presenting the experimental conditions was counterbalanced across participants.