Dietary Fiber Intake and Body Fat Gain: A Prospective Cohort Study of Middle-Aged Women

This study was conducted to determine the extent to which changes in dietary fiber consumption affect weight and body fat percentage (BF%) over time. An auxiliary objective was to examine the influence of age, total caloric intake, and physical activity (PA) on the relationship between changes in fiber intake and changes in body composition over time. Design/ Subjects: Prospective cohort design with baseline and follow-up assessments 20 months apart and 252 middle-aged women (40.1±3.0 y). Diet, particularly caloric and fiber intake, was measured using 7-day weighed food records. Body fat was assessed via the Bod Pod, and PA was measured objectively using MTI accelerometers over seven consecutive days. Statistical Analysis: Changes in weight, BF%, and fiber intake were calculated by subtracting baseline measurements from those taken at 20 months. Regression analysis was used to determine the extent to which baseline fiber intake/1000 kcal and changes in fiber intake/1000 kcal were predictive of changes in body weight and BF%. Partial correlation was employed to ascertain the effect of controlling for each of the potential confounding variables on the fiber and body composition associations. Results: Across the study, there were significant changes in all variables. For every increase of one gram of fiber/1000 kcal consumed, weight decreased by 0.55 lb (P=0.0061) and BF% decreased by 0.25 percentage point (P=0.0052). Baseline fiber intake/1000 kcal was not predictive of changes in body weight or BF% over the 20 month period. Conclusions: Increasing dietary fiber intake may be an effective means of weight management in middle-aged women.