Using a computer-based operant task and progressive ratio to estimate eating independent of hunger in obese women with binge eating disorder. J.A. Nasser, S.M. Evans, A. Geliebter, F.X. Pi-Sunyer, R.W. Foltin. New York Obesity Research Center, and Division on Substance Abuse, Columbia University College of Physicians and Surgeons, New York, NY USA. “Eating when not physically hungry” is one of the research diagnostic criteria for binge eating disorder (BED) in the DSM-IV. We used a computer-generated progressive ratio task to assess food reinforcement in 7 obese women with BED, and 11 women without BED (7 lean and 4 obese) under fasted and fed conditions. The Ss consumed 600 ml of flavored water or a 1 kcal/ml liquid meal, 2 h after a self-chosen lunch, and rated hunger on a VAS before and 15 min after consuming the preload. Ss observed the available reinforcers (non-food gifts or snack foods) for 2 min, then performed the PR task with ratios varying from 10 to 200 over 10 1-minute trials. The two groups did not differ in PR performance in the fasted condition (FBP=74±34 vs. 95±72, F=.14, p=.72). A significant difference between the non-BED and BED groups was observed in the fed condition ( F=6.5, p=.025), and there is a significant difference within the non-BED group between the fasted and fed condition ( t=−2.6, p=.03). There was no correlation between hunger ratings and FBP after consuming the liquid meal in the BED Ss ( r=.14, p=.86), however, FBP did correlate with hunger rating in the Non-BED Ss ( r=.7, p=.016). This data suggests the usefulness of operant task performance after a caloric preload to objectively model criteria for BED.