Largely due to safety considerations, many individuals have turned to dietary supplements in preference to drugs to aid in various “weight loss” regimens. Among a multitude of choices, increased dietary ­ber consumption has offered one solution. In this chapter, we will concentrate on one ­ber, chitosan. It has been proposed that oral intake of chitosan, a soluble ­ber with reputed special properties that prevent gastrointestinal absorption fat calories, offers a possible partial solution to the problem [4,5]. What do we know about chitosan?