Chitosan is a naturally occurring fiber derived from the complex sugar found in the shells of shrimp, crabs and other shellfish. Chitosan has the capacity to bind lipids and fats and stands out for its ability to trap fat before it is absorbed in the body. More importantly, since it is not digested, chitosan has no calories.

Upon oral ingestion, chitosan binds to the intestinal lining, where it tightly binds dietary fats and lipids before they are absorbed in the body. As a result, the dietary fat is prevented from entering into the bloodstream. When dietary fat is bound to the chitosan fiber, it becomes a large mass, which cannot be absorbed in the body. Chitosan fibers differ in their structure from other fibers in that chitosan possesses a net positive charge. This positive charge attracts negative charges on the fats, lipids and bile acids. Since chitosan fiber is not metabolized, it is cleared from the body along with the fat in the fecal material.

Published reports have shown that chitosan works in concert with vitamin C. It has been suggested that the action of chitosan may be enhanced by as small an amount of vitamin C as 10 mg.