Effects of Learning and Food Form on Intake in Humans

Due to the rising incidence of obesity, much emphasis has been placed on identifying mechanisms of increased energy intake. At this point, the mechanisms responsible for the recent increase in obesity prevalence have not been thoroughly examined. Pre-ingestive influences, such as cognitive factors, may play a larger role in creating an energy surplus than previously thought. Expectations about the satiating effect of a food may override the post-ingestive influences in dictating further consumption. In addition, obese individuals may exhibit a decreased compensatory response to foods as compared to lean individuals. Understanding the effects of energy content, food form, and learning on satiation, satiety, and energy intake will allow for a greater understanding of the mechanisms of energy imbalance as a whole. Food choice is dictated by sensory properties and post-ingestive effects. By utilizing foods with similar sensory properties, the acquired knowledge derived from ingesting these foods can be monitored by analyzing subsequent intake at the same meal and at subsequent eating occurrences. It is hypothesized that the liquid food form will elicit weaker dietary compensation; that is, energy intake at other eating events will not be adjusted to compensate for that food. In addition, it is posited that the lower energy food will cause lower compensation postprandially. By having participants consume the same test food daily over a two week learning period, it is thought that they will show improved dietary compensation when the initial testing is repeated due to learned associations between food properties and metabolism.