This tendency to eat more when offered more was observed nearly 30 years ago when Pudel and Oetting conducted an observational study in which they served people soup from normal bowls to determine their customary intake. On the 4th day, researchers secretly substituted trick bowls that slowly refilled from a hidden reservoir under the table.  Both obese and lean participants ate more than their usual portion.  The participants were told about the trick, and their intake was measured over the next 6 days. Normal-weight individuals adjusted their intake while obese participants continued to overeat. Tendency to Eat More

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