The effect of extracted and isolated fibers on appetite and energy intake: A comprehensive review of human intervention studies

In light of the increasing prevalence of obesity and cardiometabolic diseases, the underconsumption of fiber is concerning due to its various associated health benefits such as weight management. Adding extracted or isolated dietary fibers into various consumer products is a practical strategy for addressing the fiber gap. This comprehensive review identified evidence on the efficacy of different types of extracted and isolated fibers in reducing appetite and energy intake. Published reports of randomized controlled trials assessing appetite or energy intake in healthy adults were systematically searched, and those investigating extracted and isolated fibers following acute or chronic intake were selected. A total of 136 studies, consisting of 107 acute studies and 29 chronic studies, were included in the review. Overall, most fiber types did not show significant effects on appetite ratings and energy intakes. Acute intakes of two viscous fibers, alginate or guar gum, as well as oat fiber, were observed to most frequently result in reductions in appetite ratings. Additionally, chronic, but not acute, intakes of resistant maltodextrin/dextrin were also beneficial for appetite ratings. Viscous fibers were more likely to improve appetite ratings compared to non-viscous fibers, and fermentability did not appear to affect appetite ratings. Unfortunately, the current evidence base is highly varied due to the many differences in methodology and limited research on many of the fibers. While the possible benefits of extracted and isolated fibers on appetite sensations, food intake, and ultimately body weight regulation should not be completely dismissed, our review highlights the complexity of this research area and the gaps that need to be addressed to improve the robustness of the evidence.