ARS | Publication request: Fermentable and Nonfermentable Fiber Supplements Did Not Alter Hunger, Satiety Or Body Weight in a Pilot Study of Men and Women Consuming Self-Selected Diets

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 23, 2003
Publication Date: October 1, 2003
Citation: Howarth, N.C., Saltzman, E., Mccrory, M.A., Greenberg, A.S., Dwyer, J., Ausman, L., Kramer, D.G., Roberts, S.B. 2003. Fermentable and nonfermentable fiber supplements did not alter hunger, satiety or body weight in a pilot study of men and women consuming self-selected diets. Journal Of Nutrition 2003;133:3141-44.

Interpretive Summary: We conducted a short term, pilot study to examine whether consumption of supplements of fermentable fiber (FF) would decrease hunger and energy intake, and promote weight loss, to a greater extent than nonfermentable fiber (NFF) in free-living, ad libitum-feeding human subjects. The study was a single-blinded outpatient investigation consisting of two 3-wk phases (Phases 1 and 2) when a fiber supplement was consumed, with a 4-wk washout between Phase 1 and Phase 2. In both phases subjects were requested to increase fiber intake over the course of the first 3 days to minimize potential gastrointestinal upsets. Energy intake, hunger, satiety, and body composition were measured at different intervals. Previous research has suggested that increasing total fiber intake up to recommended levels should reduce energy intake due to decreased hunger and/or increased satiety, which in turn should cause weight loss and a reduction in the current high prevalence of obesity and overweight. However, to our knowledge there is little information on the relative effects of different types of fibers on energy. Based on the results of this study, it is reasonable to suggest no role for acceptable amounts of FF isolates in enhancing satiety and reducing energy intake in humans on an ad libitum diet. Our results suggest that fiber supplements do not automatically have a beneficial influence on energy regulation, and that if they are to be effective it would be under different conditions from those used in this study, perhaps when a longer duration was used, a larger number of more homogeneous subjects studied, or under conditions of restricted energy intake. These results suggest no role for FF and NFF isolates in promoting negative energy balance during ad libitum feeding in humans.

Technical Abstract: Little is known about the relative effects of fermentable fiber (FF) versus nonfermentable fiber (NFF) on energy regulation in humans. We compared 27±0.6 g/d supplements of FF (pectin, b-glucan) and NFF (methylcellulose) for their ability to decrease ad libitum energy intake (EI) and hunger, increase satiety, and cause spontaneous body weight and fat losses. Eleven men and women aged 23-46 y, body mass index (BMI) 20.0-34.4 kg/m2, consumed first NFF and then FF for 3 weeks each, with a 4-wk washout period between phases. Daily satiety assessed with analog scales was significantly higher with NFF than FF (60.7±1.0 mm vs. 57.7±0.8 mm, P=0.01). However, there were no significant differences in reported EI (NFF < FF by 7%, P=0.31, NFF < baseline by 9.5%, P=0.11)), body weight (NFF 0.13 kg, P=0.73; FF 0.13 kg, P=0.60) or fat percentage (NFF '0.3%, P=0.56; FF '0.1%, P=0.66) within either phase. In contrast to findings in animals, NFF was more rather than less satiating than FF, and use of neither NFF nor FF preparations was associated with body weight or fat loss. These pilot results suggest no role for short term use of FF and NFF supplements in promoting weight loss in humans consuming an ad libitum diet.