To create a behavioral classification of obesity, 2-wk baseline food diaries were obtained from 236 obese women entering weight-loss programs. Subjects monitored food intake along with the social, environmental, and emotional context in which each meal occurred. Variables representing situation-specific eating behaviors were statistically extracted from > 11 000 eating episodes. Hierarchical cluster analysis identified five distinct groups of subjects on the basis of similarity of eating patterns. The five groups were (1) moderately healthy eating habits, (2) chronic food restrictors, (3) alternating diet-binge eaters, (4) emotional overeaters, (5) unrestricted meal overeaters. The five groups differed on questionnaire measures of emotional adjustment and eating behavior but did not differ on dropout rates, amount of weight lost, or exercise compliance. The chronic food restrictors had significantly less lean body mass, lower resting metabolic rates, and higher waist-to-hip ratios than did the unrestricted meal overeaters.