Masters Theses

Date of Award

8-2015

Degree Type

Thesis

Degree Name

Master of Science

Major

Nutrition

Major Professor

Hollie A. Raynor

Committee Members

Sarah E. Colby, Melissa Hansen-Petrik

Abstract

Background: It is suggested that increasing intake of fruits and vegetables may lead to decreased energy intake via substitution of higher energy-dense foods, such as snack foods (SF; i.e. candy, chips, cookies). This study investigated the impact of increasing fruit (F; grapes) intake, via increased portion size, on SF (potato chips) intake during a meal and whether increases in F intake affected total meal energy intake, via reducing SF intake (substitutive eating), in normal-weight adults. A secondary objective investigated whether the relative reinforcing value (RRV) of SF was a moderator of the substitutive relationship between F and SF.

Methods: Using a 4X4 crossover design (between-subjects factor of order [1, 2, 3, 4] and a within-subjects factor of meal condition [CONTROL, INCREASE, DECREASE, INCREASE+DECREASE]), 25 healthy-weight participants (22.0 ± 3.7 years, 76% female, 64% white) completed the study. As part of a larger project, this ancillary study focused on the unidirectional substitution relationship between CONTROL and INCREASE. In addition to two sandwiches, CONTROL contained 100 grams (g) each of F and SF, while INCREASE contained 150g of F and 100g of SF. A validated computer task determined the RRV of SF.

Results: Analyses of variance found that participants consumed significantly more F (grams and energy) in INCREASE (141.4 ± 21.8g, 65.2 ± 11.3kcal), as compared to CONTROL (94.5 ± 16.4g, 96.2 ± 16.0kcal), but there was no significant difference in SF (grams or energy) or total energy intake in INCREASE, as compared to CONTROL. Hierarchical regressions determined that increases in F intake (grams or energy) were not significantly associated with changes in SF intake (grams or energy) or changes in total energy intake from CONTROL to INCREASE. A hierarchical regression also showed that the RRV of SF did not significantly moderate the change in SF intake from CONTROL to INCREASE.

Conclusion: Increasing F consumption in a meal did not contribute to significant decreases in SF or total energy intake in a meal, suggesting F does not act as substitute for SF. Recommendations encouraging individuals to increase F intake in order to decrease total energy intake may not achieve desired results.

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