Is flavour-nutrient learning disrupted by dietary variability?

It is widely accepted that changes in the environment are responsible for the current obesity epidemic. One feature of our current ‘obesogenic’ environment is a greater assortment of food products (multiple versions of the same type of food). Often these varieties differ considerably in their energy density (ED). One potential consequence of this increased ‘dietary variability’ is that, for any given type of food, the postingestive effects of eating are more variable and, thus, less predictable. In rodents, being able to consistently predict the energy content of a food is important for food intake control; rats that are exposed to a food that varies in its energy density tend to overeat and gain weight. Here, we tested the prospect that dietary variability may compromise food intake control in humans. Specifically, we explored the idea that ‘flavour-nutrient inconsistency’ causes uncertainty in predicting a food's postingestive effects and promotes lower expected satiety. Across eight days, participants consumed a novel smoothie and rated its liking and expected satiety; a preload compensation test was also conducted. Two versions (high ED vs. low ED) of the smoothie were created which were matched on their sensory characteristics. Using a between-groups design, participants were assigned to either a ‘Consistently HED’, ‘Consistently LED’, or ‘Inconsistent ED (4/4 days of HED/LED, randomized)’ condition. Results will assess; i) the extent to which flavour-nutrient associations causally impact expected satiety (HED v. LED) and, ii) whether inconsistent flavour-nutrient associations affect expected satiety in ways which increase one's risk of overeating.