Methods of producing low viscosity glucomannan compositions by mixing a viscosity lowering compound with glucomannan under conditions suitable to form a low viscosity glucomannan composition are disclosed. The ability to modulate (increase or decrease) viscosity by combining glucomannan with compounds of differing molecular weights is described. Also, methods for lowering blood glucose and cholesterol in mammals by administering an effective therapeutic amount of maltodextrin-glucomannan complex are described. Additionally, methods for converting a food or beverage product from an initial low viscosity substance to a high viscosity end-product are also described herein.