A Personalized Whole-Food Diet Differentially Modulates Glucoregulatory and Cognitive Responses Compared With Conventional Dietary Counseling in Young Black and White Adults With Overweight or Obesity: An 8-Week Randomized Controlled Trial

Background: Black adults bear a disproportionate burden of cardiometabolic dysfunction, yet most dietary trial evidence comes from predominantly White cohorts. Objective: To evaluate whether a personalized whole-food dietary intervention improves cardiometabolic outcomes more in Black than White young adults with overweight or obesity. Methods: In this 8-week randomized, controlled trial (ClinicalTrials.gov: NCT04635917), 112 Black and White adults (18-35 years; BMI 25-45 kg/m2) were block-randomized by race to a personalized dietary intervention providing whole foods (PD, n=57) or conventional dietary counseling at baseline (BL) using MyPlate guidelines (CD, n=55). Primary outcomes were Matsuda Index and fasting and OGTT-derived glucose, insulin, and non-esterified fatty acids. Other glucoregulatory, cardiovascular, anthropometric, appetite, and cognitive outcomes were also assessed. Outcomes were analyzed using baseline-adjusted linear models with sensitivity analyses adjusting for baseline BMI and food security score. Results: Compliance with study food consumption was 85-91%. Diet quality was higher in PD than CD (P < 0.05), with larger gains in vegetable-related outcomes among Black participants (group x race, P < 0.05). HOMA-{beta} was lower in PD than CD overall (P < 0.05). In sensitivity analyses, Black PD participants had greater fasting insulin reductions than White, especially in the latter half of intervention (week x group x race, P < 0.05), with a similar tendency for HOMA-IR. Glucose AUC 0-30 min was higher in White than Black PD participants (group x race, P < 0.05). Concentration performance was higher in PD than CD overall (P < 0.05), with larger gains in processing speed and accuracy among Black than White participants (group x race, P < 0.05). No effects were observed for cardiovascular or appetite outcomes. Conclusions: The personalized whole-food intervention produced differential effects in fasting insulin and early-phase glucose handling, and greater benefits in attention, in Black compared with White young adults with overweight or obesity during weight maintenance.