Effects of daily snack food intake on food reinforcement
Clark, Erika N.
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The reinforcing value of food plays a role in determining the type and amount of food that people consume. A previous study from our group showed that when participants ate a 200-300 kcal portion of a highly liked food daily for 14 days, the reinforcing value of that food was decreased, as was laboratory energy intake. However, this study was conducted only in non-obese participants. Recently a follow-up study was completed in both non-obese and obese participants and showed that, unlike the non-obese participants, obese individuals showed a significant increase in the reinforcing value of high energy density snack food after two weeks of daily consumption. This suggests that the mechanisms that underlie the development of food reinforcement differ between non-obese and obese individuals. The purpose of my thesis was to determine whether this differential effect in non-obese and obese participants is specific to high energy density (HED) snack foods. Participants had food reinforcement and liking tested at baseline and then again after two weeks of daily consumption of 60 gram portions of a HED or low energy density (LED) snack food. Results showed that there was a decrease in food liking and food reinforcement in non-obese participants from baseline to post-daily intake. This effect was observed regardless of food type (HED vs. LED). In obese participants, food reinforcement increased and liking decreased for HED foods from baseline to post-daily intake, but food reinforcement decreased for LED foods and liking was unchanged from baseline to post-daily intake. This replicates our previous work on difference in responses to daily intake of HED snack foods between obese and non-obese participants and extends these findings by showing that this difference is specific to HED foods. In addition, as shown previously, there is a dissociation between self-reported food "liking" and food "wanting" in obese, but not non-obese women.