One aspect of the invention provides dietary fiber compositions comprising effective amounts of glucomannan, xanthan gum, and alginate to produce a desired viscosity. The invention also provides food products comprising an effective amount of a dietary fiber composition. In other aspects, the invention provides methods for preparing a dietary fiber composition or a food product comprising a dietary fiber composition and methods for promoting satiety, promoting weight loss, lowering blood glucose levels, or lowering blood cholesterol levels in a mammal.