We examined the dietary fiber intake, food sources of dietary fiber, and relationship of dietary fiber with body composition and metabolic parameters in college students with plausible dietary reports.
Research Methods & Procedures
Students (18–24 yrs) provided data on anthropometry, fasting blood chemistries, and body composition (bioelectric impedance). Diet and physical activity were assessed with the Diet History Questionnaire and the International Physical Activity Questionnaire. Plausible dietary reporters were identified (± 1 SD cutoffs for reported energy intake as a percentage of predicted energy requirement). Multiple regression analyses were conducted with the total (n=298) and plausible (n=123) samples, adjusting for age, race, sex, smoking status, physical activity, energy intake, and fat free mass (where applicable).
Food sources of dietary fiber were similar in males and females. In the plausible sample compared to the total sample, dietary fiber was more strongly associated with fat mass (β=−0.24, p<0.001), percent body fat (β= −0.23, p<0.001), BMI (β= −0.11, p<0.01), waist circumference (β= −0.67, p<0.05), and fasting insulin (β= −0.15, p<0.001). When the effect of sex was investigated, dietary fiber was inversely related to fasting insulin and fat mass in men and women and inversely related to percent body fat, BMI, and waist circumference in men only (p<0.05).
Inclusion of implausible dietary reports may result in spurious or weakened diet-health associations. Dietary fiber is negatively associated fasting insulin levels in males and females and consistently associated with adiposity measures in males.