Scientists Figure Out Why Fiber Fills You Up And it could lead to an anti-hunger pill By Matt Cantor, Newser User Posted May 2, 2014 9:40 AM CDT 14 comments Comments Fiber makes us feel full thanks to the action of a chemical called acetate, scientists say. (Shutterstock) (Newser) – Experts have long suggested that fiber keeps us feeling full because it takes a long time to digest, but new research challenges that notion—and may point the way to a new anti-hunger pill. The key is a short-chain fatty acid called acetate, which emerges as fiber is digested. Acetate then makes its way to the brain's hypothalamus, where it builds up and triggers chemical reactions that tell us we're full, Time reports. Researchers reached this conclusion by scanning the progress of a dietary fiber called inulin through the bodies of mice. Those mice who ate fatty diets rich in inulin gained less weight than mice who didn't eat inulin. But one electrophysiologist not related to the study points out that the mice were fed dietary fiber levels of about 11%. He tells Nature that at such a level, "the room would be full of mouse farts"—and perhaps the mice were eating less because they felt gassy. The researchers plan to next test the idea in humans. So could we eventually see an acetate-based diet pill? It's possible, the Telegraph suggests: "The major challenge is to develop an approach that will deliver the amount of acetate needed to suppress appetite but in a form that is acceptable and safe for humans," a researcher says.