Mindful eating: Memory for meal size controls hunger in the inter-meal interval

In this study we explored the hypothesis that visual information plays a causal role in the satiety that is experienced after a food has been consumed. Before lunch, half of our participants were shown 300 ml of soup and half were shown 500 ml. Orthogonal to this, half consumed 300 ml and half consumed 500 ml. This process yielded four separate groups (25 participants in each). Independent manipulation of the ‘actual’ and ‘perceived’ soup portion was achieved using a computer-controlled peristaltic pump. This was designed to either refill or draw soup from the soup bowl in a covert manner. Immediately after lunch, self-reported hunger was predicted by the actual and not the perceived amount of soup consumed. However, two and three hours after meal termination this pattern was reversed. Hunger was predicted by the perceived amount (participants who thought they had consumed the 500 ml portion reported significantly less hunger) and not the actual amount. This independent manipulation of perceived and actual intake reveals the separate contribution of memory processes and post-ingestive signals to satiety. Together, our findings confirm a role for ‘expected satiety’ and show how memory for a recent eating episode can affect satiety in the inter-meal interval.