Objective: The current study tests the influence of two factors, the obesogenic environment and impulsivity, on food intake in primary school children. Our current food environment offers a large variety of cheap and easily available sweet and fatty foods. This obesogenic environment is believed to be a cause of the recent obesity epidemic. Impulsive people are generally less successful at inhibiting prepotent responses and they are reward sensitive. We investigate whether the interaction between an obesogenic environment and an impulsive person leads to overeating. Design: A quasi-experimental 2 (reward sensitive versus not reward sensitive) by 2 (successful response inhibitors versus unsuccessful response inhibitors) by 2 (monotonous versus varied food environment) between-subjects design with caloric intake during a taste test as the main dependent variable. The link between impulsivity and overweight was also examined. Subjects: 78 healthy primary school children (age: 8-10 years). Measurements: We measured two aspects of impulsivity: reward sensitivity and deficient response inhibition. Subsequently, one aspect of the obesogenic environment was manipulated; half of the participants received monotonous food during a bogus taste test whereas the other half tasted food that was varied in colour, form, taste and texture. Results: As expected, reward sensitivity interacted with variety. In the monotony group there was no difference in food intake between the less and more reward-sensitive children (183 kcal ± 23 s.d. versus 180 kcal ± 21 s.d.). However, in the variety group the more reward-sensitive children ingested significantly more calories than the less reward-sensitive children (237 kcal±30 s.d. versus 141 kcal ± 19 s.d.). Reward sensitivity was not linked to overweight. Deficient response inhibition did not interact with variety, but it was linked to overweight. Conclusion: It is suggested that reward sensitivity could be a causal mechanism for overeating in an obesogenic environment whereas prepotent response inhibition may be a maintaining factor of the problem of overeating.

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Objective: It has been shown repeatedly that impulsivity, obesity and food intake are related; obese people are more impulsive than lean people and impulsive people eat more than less impulsive people. The relation between impulsivity and food intake might be state dependent; hunger motivates food seeking behaviour and food consumption, especially of high caloric food. Difficulties to overrule automatic behavioural tendencies might make impulsive people more susceptible to the effects of hunger on food selection. Therefore, they are expected to increase their intake more than low impulsive people when feeling hungry. Study 1: Fifty-seven female participants were randomly assigned to a hunger or sated condition. Response inhibition (a measure of impulsivity) and food intake were measured. Results show that impulsive participants ate significantly more, but only when feeling hungry. Study 2: Ninety-four undergraduate students participated. Hunger, response inhibition and the purchase of food in a virtual supermarket were measured. The same interaction was found: impulsive participants bought most calories, especially from snack food, but only when feeling hungry. Conclusion: Hunger and impulsivity interact in their influence on consumption. These data suggest that reducing hunger during calorie restricting diets is important for successful weight loss, particularly for the impulsive dieters.

Previous research has linked overeating and overweight/obesity to impulsivity. To find out whether impulsivity causes overeating and hence overweight and obesity, we attempted to prime the concept of impulsivity in healthy participants. In a within-subjects design one sample participated in two conditions. In both conditions participants did a priming task that either hinted subtly at the concept of impulsivity or that was neutral in content. Each time the priming task was followed by a bogus taste test. Trait impulsivity was measured by means of a behavioural task and self-report. Firstly, we hypothesized that participants would eat more during the taste test after they had been primed with the concept "impulsivity" compared to after the control session. Secondly, we expected that a more impulsive personality would predict a heightened food intake. Thirdly, we expected that impulsivity would predict food intake better than restraint. The results showed that both the self-report measure of impulsivity and the behavioural task predicted food intake. Restraint did not significantly predict food intake. Primed impulsivity did not increase food intake, possibly because the priming effect did not last long enough.

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