Virginia Tech® home

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

Insert your title here

Your Text Here
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, DiFeliceantonio Lab, Fralin Biomedical Research Institute at VTC
March 23, 2026, at 1 p.m.
Room G101 A/B, 4 Riverside Circle
Watch via Zoom
Visit the DiFeliceantonio Lab

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 Developmental Biology

Training

Graduate Research Assistant, DiFeliceantonio Lab, Fralin Biomedical Research Institute at VTC

Mentor

Alexandra DiFeliceantonio, Ph.D., Assistant Professor and Interim Co-director, Center for Health Behaviors Research, Fralin Biomedical Research Institute at VTC

Committee Members

Publications

Leslie, E., Rego, M. L. M., Yu, W., Sullivan, R., Kolb, R., Lee, H., Groccia, A., Ahrens, M. L., Katz, B., Davy, K. P., Hedrick, V. E., Davy, B. M., & DiFeliceantonio, A. G. Ultra-Processed Food Intervention Alters Brain Response in Adolescents but not Young Adults. In preparation.

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

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. Oral presentation.

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. Oral presentation.

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. Oral presentation. 

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. Poster presenation.

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. TBMH poster presentation.

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. TBMH poster presentation.

  • Student of the Year Award, Community, Translational Biology, Medicine, and Health Graduate Program — 2023
  • Flip the Fair Overall Winner, Virginia Tech — 2023
  • Ray Gaskins Health Science Fellowship, Fralin Biomedical Research Institute at VTC — 2023
  • Health Sciences and Technology Hokie Pitch "Shark Tank" competition, 1st Place (CytoKure) , Fralin Biomedical Research Institute at VTC — 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 Translational Biology, Medicine, and Health Graduate Program Recruitment Event — 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
  • Flip the Fair (STEM outreach; 5th-grade student judges) — 2023