Chitosan products do not work...sorry...
http://www.quackwatch.com/04Consumer.../chitosan.html
Here's a link to an article on Dr. Barrett's Quackwatch site - there's some other links as well that will answer your question before you go spending money.
Interestingly, the Enforma company (makers of the heavily advertised "Fat Trapper" and "Exercise in a Bottle" products - don't those names just
scream SCAM to you??) were fined $10 million last year for false and fraudulent advertising by the FDA - there's a link to that FDA press release as well...
Take care...