Abdominal adiposity is a greater risk factor for metabolic and cardiovascular diseases than overall obesity. The role of carbohydrate quality in abdominal weight gain is not fully understood. We aimed to examine the prospective relationship between a carbohydrate quality index (CQI), as well as different fiber measures, and changes in weight and waist circumference (WC), a surrogate marker of abdominal adiposity, over 18 years of follow-up.
Subjects were participants in the Framingham cohort (3,513 subjects, 13,834 unique observations) with mean baseline age 54.2 years (SE=0.16) and mean BMI 27.3 kg/m2 (SE=0.11). Diet was assessed using a semi-quantitative food-frequency questionnaire. The CQI was defined by four criteria: dietary fiber, glycemic index, ratio of whole grain to total grain, and ratio of solid to total carbohydrate. The CQI and fiber exposures were grouped into quartiles. Estimates of weight and WC were standardized to four-year change and examined using mixed models accounting for repeated measures.
After adjustment for demographic and lifestyle factors, although statistically significant, the association between CQI and change in WC was not clinically meaningful (Q1: 1.95 cm vs Q4: 1.98 cm). No association was observed with CQI and weight change. Significant associations were observed between total and cereal fiber and change in WC, with cereal fiber having the strongest inverse relationship (Q1: 2.74 vs Q4: 1.25 cm, p<0.001). Cereal fiber was also the only measure to be inversely associated with 4-year weight gain (p=0.004). A strong inverse association was observed for the ratio, cereal fiber-to-total carbohydrate, and change in waist (Q1: 2.61 cm vs Q4: 1.23 cm, P<0.0001) and weight (Q1: 0.33 versus Q4: 0.04 kg).No associations were observed for fruit or vegetable fiber.
Carbohydrate quality and, in particular, cereal fiber, may be an effective dietary modification to attenuate abdominal weight gain and reduce cardiometabolic disease risk.