The aim of this study was to investigate changes in emotional state, food perception and cognition following administration of small quantities of low-, medium- or high-energy food. Thirty-eight female dieters and non-dieters aged 18–51 years (mean BMI=24.6 kg m−2) were asked to rate their emotional state before and after consumption and dietary restraint was determined using the Three-Factor Eating Questionnaire (Stunkard & Messick, 1985). The results showed that participants felt fuller and more energetic as energy content increased, whereas perception of “healthiness” and “safeness” of food decreased. Higher levels of anxiety were observed after ingestion of the medium-energy than after the low-energy food. Irrespective of the energy content, restrained eaters felt significantly more energetic than non-restrained eaters, whereas dieters reported significantly lower positive mood ratings than non-dieters following food administration. Although no significant effect of dietary restraint, dieting or energy content was observed on working memory, dieters’ performance was lower after consumption of a high-energy food. In conclusion, the study provided further evidence that energy content and psychological features of foods can alter emotional state and it can be tentatively suggested from these data that psychologically mediated changes in emotional responses to food and, more specifically, participants’ dieting behaviour should be taken into account when assessing the effects of nutrition on mood and cognition.