How Does Glucomannan Work?Glucomannan works like any other fiber product to relieve constipation, lower cholesterol, as well as to help with obesity and type 2 diabetes. It is a fiber that is not absorbed into the body (it stays in the digestive tract). It increases water absorption into the stool in the colon, helping to relieve constipation. Glucomannan probably works to lower cholesterol by helping the body get rid of cholesterol through the stool. Because fiber slows the emptying of the stomach, it can help people feel full and can help keep blood sugar more even. This is probably how glucomannan fiber helps with obesity and type 2 diabetes.