Reinforcing value of food in obese and non-obese women.

Food is a powerful reinforcer, and individual differences in the reinforcing efficacy of food may provide a mechanism to explain the excess intake and positive energy balance responsible for obesity. The present study tested the hypothesis that eating palatable food would be more reinforcing than engaging in sedentary activities (e.g. playing computer games) for obese in comparison to non-obese non-dietary restrained female college students. Subjects could choose to eat food or engage in sedentary activities based on their responding in a computer-generated concurrent schedules task. The reinforcement schedule associated with earning access to sedentary activities was held at variable ratio 2 (VR2) while the food reinforcement schedule was set at VR2 in the first trial of the choice task and doubled across the four subsequent trials from VR4 to VR32. Choice and consumption results indicated that eating was significantly more reinforcing than engaging in sedentary activities for obese subjects than non-obese subjects. Hedonics for the activities and foods were not correlated with total food reinforcers earned and did not differ between the groups. These results confirm the hypothesis that eating food is more reinforcing than selected alternative activities to a greater extent for obese than for non-obese young women.