A great deal of effort is being expended to investigate the biogenetic basis of the development and maintenance of obesity and the regulation of food intake. The task of developing and validating theoretical models of the regulation of food intake and its relationship to body weight is hampered by a lack of basic descriptive data. This study investigated the eating behavior of 96 obese women by conducting a microanalysis of 2-week baseline behavioral eating diaries. Subjects were in approximate energy balance consuming a high-fat diet (41 percent of kcal from fats) averaging 1978 kcal/day. Self-reported episodes of overeating and impulsive eating occurred frequently and were associated with situational antecedents such as eating in the car, snacking alone, friends, restaurants, availability of forbidden foods, craving sweets, tired, irritable, bored, depressed, and skipping meals. Markov chain analysis showed that overeating and impulsive eating were positively autocorrelated, suggesting the presence of an abstinence violation effect. These data suggest that eating behavior is often controlled by environmental, cognitive, and affective variables and that a complete understanding of obesity will require an integrated biobehavioral approach.