Abstract P066: A Refined Carbohydrate Diet Attenuates Weight Loss in Insulin Resistant Individuals

Abstract

Introduction: Weight loss is attenuated in individuals with insulin resistance (IR) who follow a traditional high-carbohydrate, calorie-restricted diet. However, the type of carbohydrate may modulate this response. We studied the effects of whole grains vs. refined grains on weight loss in individuals with increased waist circumference (M: >102 cm, F: >88 cm) and at least 1 other metabolic syndrome characteristic. Hypothesis: In a secondary analysis, we hypothesized that IR individuals (estimated by a triglyceride:high-density lipoprotein cholesterol ratio > 3.5) would lose more weight on a hypocaloric diet with whole grains vs. refined grains. Methods: Overweight or obese (BMI 25–42 kg/m2) men and women (n=50) 35–55 yrs were randomized to a controlled-feeding diet with whole vs. refined grains for 12 weeks [6 weeks isocaloric then 6 weeks hypocaloric (∼500 kcal/d)]. Results: [All comparisons represented as IR mean±SEM vs. insulin sensitive (IS) mean±SEM, p-value)]. Compared to the IS group (n=29), the IR group (n=21) was predominately male (14 M/7 F vs. 11M/18F, p=0.04), weighed more (107.5±3.3 vs. 93.9±3.0 kg, p=0.005), and had increased waist circumference (113±2.2 vs. 106±1.5 cm, p=0.02). IR status did not affect overall percent body weight (%BW) lost over the course of the study (−4.0±0.4 vs. −4.5±0.3 %BW; p for interaction, time x IR status = 0.34). However, IR status did affect %BW lost when the type of carbohydrate was considered (p for interaction, time x IR status x diet = 0.04; Figure ). Post-hoc analysis revealed that within the refined grain group, IR participants lost less %BW than the IS participants (−4.14±0.4 vs. −5.84±0.5 %BW, adjusted p=0.04). On the whole grains diet, %BW lost was similar in the IS and IR groups. Conclusion: In conclusion, IR individuals lost less %BW than IS individuals on the hypocaloric refined grain diet. Limiting refined grains may improve the efficacy of traditional weight loss diets in IR individuals. Figure. %BW lost in IR and IS groups on refined grain diet, *p=0.04.