Could a Common Fiber Outpace Ozempic? In Mice, Beta-Glucan Slashes Fat While Other Fibers Do Not
A form of dietary fiber called beta-glucan, found in oats and barley, can help regulate blood sugar and support weight loss in mice fed a high-fat diet. In a study from the University of Arizona and the University of Vienna, beta-glucan reduced body weight and fat content within 18 weeks, while other fibers such as wheat dextrin, pectin, resistant starch, and cellulose did not produce the same weight loss, even though they significantly altered the gut microbiome. Researchers caution that results in mice do not automatically translate to humans, but the findings highlight that fiber type matters for metabolic health and could guide future dietary guidance and agricultural production. With less than 5 percent of Americans meeting the daily fiber recommendation, the question becomes: which fiber should people actually choose?
Beta-Glucan Triggers Gut Shifts and Metabolic Wins
Beta-glucan uniquely increased the presence of Ileibacterium in the mouse gut, a bacterium that has been linked to weight loss in prior studies. From early in the study, mice fed beta-glucan showed lower body weight and lower body fat than mice fed other forms of fiber. In a related line of experiments, barley flour rich in beta-glucan produced higher energy expenditure and weight loss in rodents, even though the animals continued to eat the same amount of high-fat food. Mice fed beta-glucan also had higher levels of butyrate in their guts, a metabolite produced when microbes break down fiber. Butyrate can trigger the release of glucagon-like peptide-1 (GLP-1), the natural peptide that some drugs mimic to stimulate insulin release. "Part of the benefits of consuming dietary fiber is through the release of GLP-1 and other gut peptides that regulate appetite and body weight," said Duca.
From Mice to Humans: The Limits, the Hopes, and What It Means for Diet
But the study's authors caution that findings in mice are not automatically transferable to humans. The research appeared in the Journal of Nutrition, with an earlier version published in July 2024. They note there is no single fiber solution; the wide variation among fiber types matters for health, and scientists aim to inform both consumers and agricultural producers. On a public-health level, many Americans fall short of fiber intake: fewer than 5% meet the recommended 25–30 grams per day, while fiber supplements and ‘invisible fiber’ foods are increasingly common. Duca summarizes the goal: while fiber is beneficial, more human studies are needed to determine which fibers best support weight management and glucose balance. "We know that fiber is important and beneficial; the problem is that there are so many different types," said Frank Duca.
