We are what we (think we) eat: The effect of expected satiety on subsequent calorie consumption

Varying expected satiety (ES) for equi-calorie portions of different foods can affect subsequent feelings of hunger and fullness and alter consumption. To our knowledge, no study has manipulated ES for an equal portion of the same solid food, appetite has not been measured >3 h and studies have not consistently measure later consumption. It is also unclear whether changes in hunger, fullness or later consumption are related to a physiological response. The aims of this study were to use the same solid food, to measure participants' response over a 4-h inter-meal period, to measure later consumption and to assess whether any effect of ES was related to a physiological (i.e. total ghrelin) response. Using a within-subjects design, 26 healthy participants had their ES for omelettes manipulated experimentally, believing that a 3-egg omelette contained either 2 (small condition) or 4 (large condition) eggs. When ES was higher (large condition) participants ate significantly fewer calories at a lunchtime test meal (mean difference = 69 kcal [± 95% CI 4–136]) and consumed significantly fewer calories throughout the day (mean difference = 167 kcal [± 95% CI 26–309]). As expected, there was a main effect of time on hunger and fullness, but no main effect of ‘portion size’ (p > .05). There was also a significant interaction between time and portion size for hunger. There was no evidence for any significant differences being the result of changes in total ghrelin. Overall, the data suggest that ES for a solid food can be manipulated and that, when given at breakfast, having a higher ES for a meal reduces lunchtime and whole day caloric consumption.