The eating behavior of obese patients and of subjects who had normalized their body weight following biliopancreatic diversion (BPD) was assessed by a three-factor eating questionnaire (TFEQ), constructed to measure cognitive dietary restraint, the tendency to disinhibition, and susceptibility to hunger. In the obese patients higher values of both disinhibition and hunger score were found than in normoweight persons. In BPD subjects a negative association between the time elapsed from the operation and both the disinhibition and hunger score values was observed. In patients operated more than 2 years before, the eating behavior, as assessed by the TFEQ, was similar to that of normoweight persons. After BPD the operated subjects do not have to respect any dietary advice, the loss of weight and the maintenance of a normal body weight occurring in spite of an absolutely free food consumption. Similarity to the control values of disinhibition and hunger score following BPD suggests that in the long term, when the preoccupation with food and diet is abandoned, a normal eating pattern can be achieved.