Americans need more fiber in their diets, and they’re going to get it—that is, if food manufacturers have their way. According to market researcher Frost & Sullivan, the U.S. market for prebiotic—or soluble fiber—ingredients is forecast to double in the next five years to more than $220 million by 2016. But the factors that will fuel growth are still up for debate.

Right now, consumer interest in the category may have more to do with concerns about weight management than digestive health. For example, inulins—prebiotic additives generally derived from chicory root—often are used by food manufacturers as replacements for fat and sugar. Scan any yogurt or energy bar section at a grocery store, and you’ll see that the marketing on these product packages follows suit. Words like “low fat” or “no added sugar” are commonplace.

“Many of the protein and diet snack bars that we carry contain inulin, and they are popular, but not because of the prebiotic content,” said Lani Jacobs-Banner, assistant manager for the nutrition education department with Natural Grocers by Vitamin Cottage. At the western chain’s stores, customers can grab handouts describing the many benefits of prebiotics like inulin and fructo-oligosaccharides, including how they can help increase healthy bacteria present in the gut. But these facts aren’t selling points—yet. “Rarely do we have a customer who asks for a prebiotic-infused product,” Jacobs-Banner said. “Most commonly they are looking for a fiber-containing product or a diet product.”