Dietary recommendations to reduce risk of major chronic diseases consistently include the substitution of whole grains for refined grains. However, the strength of evidence to support this is “moderate” due to reliance on epidemiological data and mixed results from free‐living clinical trials. Therefore, a 12‐week randomized, parallel‐arm, controlled‐feeding, weight‐loss study was designed to determine the biological effects of chronic whole and refined grain intake on cardiometabolic risk factors in participants with “pre‐metabolic syndrome (MetSyn).” Overweight or obese (BMI 25–42 kg/m2) men (n=25) and women (n=26) aged 35–55 with increased waist circumference and at least 1 other MetSyn characteristic were randomized to either a whole (WG) or refined grain (RG) diet. Weight was maintained for 6 weeks then weight loss was induced for 6 weeks via reduced‐calorie diet (~500 kcal/d). The macronutrient profiles of WG and RG diets were matched (~54% CHO, ~17% PRO, ~29% FAT, ~6.7% SFA) with the exception of fiber due to the whole grains (WG: 7 serv WG/d, 39 g fiber/d; RG: 0 WG serv/d, 22 g fiber/d in 2100 kcal/d diet). We hypothesize that a diet containing whole versus refined grains will elicit improvements in abdominal adiposity, inflammation, and endothelial function, which are clinical targets of cardiometabolic disease that present in MetSyn. This study is supported by General Mills.Grant Funding Source: General Mills