OBJECTIVE: To describe the research methods used for the Diet and Health Study, a pilot-feasibility study to assess the impact of a whole-food plant-based vegan diet on college students' physical and mental health. DESIGN: This 3-week theory-based pilot-feasibility study will employ a stratified, randomized control design (2 intervention groups and 1 comparison group) with measurement of primary and secondary outcomes at baseline and postintervention and end-of-study focus groups. SETTING: Southeastern public state university. PARTICIPANTS: Sixty undergraduate college students aged 18-25 years. INTERVENTION: The study and intervention delivery were designed using an integration of the Theory of Planned Behavior and Social Cognitive Theory. Three consecutive weekly nutrition education lunch-and-learn sessions (75 minutes each) will be delivered using 2 different teaching modalities (ie, interactive-experiential vs lecture-based). MAIN OUTCOME MEASURES: (1) Feasibility and acceptability of study procedures and theoretically-informed whole-food plant-based vegan diet intervention; (2) potential impacts of the intervention on intrapersonal, physical, and mental health, and dietary measures; and (3) potential differential impacts of 2 intervention modalities. ANALYSIS: Descriptive statistics and effect sizes to assess changes to the outcome variables from baseline to postintervention across the 3 groups. Qualitative content analysis of the focus group transcripts.