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Dissertation Defense: The Impact of Controlled Diets High-In and Free of Ultra Processed Foods on Behavior and Brain in Emerging Adulthood

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Emma Leslie

Dissertation Defense: The Impact of Controlled Diets High-In and Free of Ultra Processed Foods on Behavior and Brain in Emerging Adulthood

Emma Leslie

Graduate Student, Translational Biology, Medicine, and Health
Graduate Research Assistant, Donnut Lab
March 23, 2026, at 1 p.m.
4 Riverside, FBRI, Room G101 A/B
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About this Dissertation

Ultra-processed foods (UPF) comprise over half of the American diet and have been linked to poor health outcomes. Emerging adulthood (adolescence and young adulthood) represent critical periods of executive function development, during which UPF consumption is highest. This crossover randomized controlled feeding trial examined the effects of UPF consumption on cognition, brain function, and eating behavior in individuals aged 18–25 years. Participants completed two 14-day controlled diet conditions in random order: a high UPF diet (81% energy from UPF) and a NonUPF diet (0% energy from UPF). Cognitive testing and functional magnetic resonance imaging (fMRI) were conducted before and after each diet to assess executive function, delay discounting, and brain response to milkshake. Following each intervention, participants completed an ad libitum buffet meal containing matched UPF and NonUPF foods to evaluate eating behavior.
Removal of UPF from the diet improved inhibitory control as measured by the Flanker task. In adolescents (18–21 years), orbitofrontal cortex (OFC) response to milkshake consumption decreased following the UPF diet and increased following the NonUPF diet, whereas young adults (22–25 years) showed no changes. Habitual UPF intake was positively associated with OFC response independent of experimental diet condition. Additionally, entorhinal cortex response predicted subsequent energy intake at the buffet meal. Together, these findings demonstrate that UPF consumption may alter executive function, food valuation, and eating behavior in adolescents and young adults.

More About the Candidate and Project

Education

Virginia Tech, Translational Biology, Medicine, and Health, Ph.D. Candidate

Kennesaw State University, B.S. Cellular, Molecular, and Development Biology

Training

Graduate Research Assistant, The Donnut Lab

Mentor

Alex DiFeliceantonio, Ph.D., Assistant Professor, Department of Human Nutrition, Foods, and Exercise; Assistant Professor, Fralin Biomedical Research Institute at VTC; Interim Co-Director, Center for Health Behaviors Research

Committee Members

Publications

 

  • Leslie, E., Rego, M. L. M., Yu, W., Ahrens, M. L., Katz, B., Davy, K. P., Hedrick, V. E., Davy, B. M., & DiFeliceantonio, A. G. A Controlled Diet Free of Ultra-Processed Food Improves Inhibitory Control in Young Adults. Under review (Journal of the Academy of Nutrition and Dietetics).
  • Rego, M. L. M., Leslie, E., Schmall, E., Capra, B., Hudson, S., Ahrens, M. L., Katz, B., Davy, K. P., Hedrick, V. E., DiFeliceantonio, A. G., & Davy, B. M. (2025). The influence of ultraprocessed food consumption on energy intake in emerging adulthood: A controlled feeding trial. Obesity (Silver Spring). Published online Nov 19, 2025. (Featured on journal cover.)
  • Joyce, J. D., Moore, G. A., Goswami, P., Harrell, T. L., Taylor, T. M., Hawks, S. A., Green, J. C., Jia, M., Irwin, M. D., Leslie, E., Duggal, N. K., Thompson, C. K., & Bertke, A. S. (2024). SARS-CoV-2 rapidly infects peripheral sensory and autonomic neurons, contributing to central nervous system neuroinvasion before viremia. International Journal of Molecular Sciences, 25(15), 8534.
  • Rego, M. L. M., Leslie, E., Capra, B. T., Helder, M., Yu, W., Katz, B., Davy, K. P., Hedrick, V. E., Davy, B. M., & DiFeliceantonio, A. G. (2023). The influence of ultra-processed food consumption on reward processing and energy intake: Background, design, and methods of a controlled feeding trial in adolescents and young adults. Contemporary Clinical Trials, 135, 107381.
  • Leslie, E. H., Kelly, A., & DiFeliceantonio, A. G. (2024). Dopamine magnitude and timing in food reward. In A. G. DiFeliceantonio (Ed.), Food & Addiction: A Comprehensive Handbook. Oxford University Press.

Presentations

Oral Presentations

  • Leslie, E. H. (2025). Influence of Ultra-Processed Foods on the Young Adult Brain. Guest lecture, Research Methods, Human Nutrition Foods and Exercise, Virginia Tech.
  • Leslie, E. H., Rego, M., Capra, B., Yu, W., Ahrens, M., Hanlon, A. L., Hedrick, V. E., Davy, K. P., Katz, B., Davy, B., & DiFeliceantonio, A. G. (2024). Exposure to Ultra-Processed Foods Alters Brain Response to Milkshake in Adolescents and Young Adults. Society for the Study of Ingestive Behaviors (SSIB), Chicago, IL.
  • Leslie, E. H., Rego, M., Capra, B., Yu, W., Ahrens, M., Hanlon, A. L., Hedrick, V. E., Davy, K. P., Katz, B., Davy, B., & DiFeliceantonio, A. G. (2024). Exposure to Ultra-Processed Foods Alters Brain Response to Milkshake. Research in Progress Seminar, Fralin Biomedical Research Institute, Roanoke, VA.



Posters

  • Leslie, E. H., Rego, M., Capra, B., Yu, W., Helder, M., Ahrens, M., Hanlon, A. L., Davy, B., & DiFeliceantonio, A. G. (2023). Influence of Ultra-Processed Food on Brain Reward and Energy Intake. SSIB, Portland, OR.
  • Leslie, E. H., Rego, M., Capra, B., Yu, W., Helder, M., Ahrens, M., Hanlon, A. L., Davy, B., & DiFeliceantonio, A. G. (2023). Influence of Ultra-Processed Food on Brain Reward and Energy Intake.
  • Leslie, E. H., Rego, M., Capra, B., Yu, W., Helder, M., Ahrens, M., Hanlon, A. L., Davy, B., & DiFeliceantonio, A. G. (2022). Methods and Design for Randomized Controlled Trial Investigating Ultra-Processed Food Consumption in Young Adults.
  • Student of the Year Award, Community, Virginia Tech TBMH — 2023
  • Flip the Fair Overall Winner — 2023
  • Ray Gaskins Health Science Fellowship — 2023
  • Shark Tank Commercialization Competition, 1st Place (CytoKure) - 2020
  • Wellness Chair, Roanoke Graduate Student Association, Virginia Tech — 2023–2024
  • Social Committee Chair, Roanoke Graduate Student Association, Virginia Tech — 2022–2023
  • Keynote Speaker, Virginia Tech TBMH Recruitment Event — 2023
  • Flip the Fair (STEM outreach; 5th-grade student judges) — 2023
  • Bodies and Bites Volunteer, Roanoke, VA — 2022–Present
  • Regional Science Fairs Judge, Roanoke, VA — 2021–Present
  • Invited Speaker, Science on Tap New River Valley: “A virus walks into a bar” — 2021