Emotional states and situations can affect food intake. We predicted that underweight individuals would eat less and overweight individuals would eat more during negative as well as positive emotional states and situations. Questionnaires to assess eating during emotional states and situations were distributed and collected in person in several major university and public libraries. Ninety questionnaires, representing for each gender the 15 most overweight, the 15 closest to normal weight, and the 15 most underweight, were analyzed. Gender had only minor effects on the eating ratings, and therefore the results are presented for the sexes combined. Underweight individuals reported eating less (P=.000) than both the normal and overweight groups during negative emotional states and situations. More surprisingly, underweight individuals also reported eating more (P=.01) than the other groups during positive emotional states and situations. Thus, part of the prediction was confirmed: the relative undereating by the underweight group, and the relative overeating by the overweight group during negative emotional states and situations. As compared to their usual eating behavior, undereating by underweight individuals during negative emotional states and situations was of a greater magnitude than their own overeating during positive states and situations (P=.01). Undereating by underweight individuals when experiencing negative emotions may contribute to their low body weight.