Can taking supplements made from shells really help you lose weight? The suppliers of chitosan diet supplements would like you to think so.

Chitosan comes from shells of crustaceans, like shrimp and lobster, and is claimed to facilitate weight loss by absorbing dietary fat. The prevailing theory is that the positively charged chitosan molecules bind to negatively charged fat molecules. The result: a portion of the fat you consume is not absorbed and will be passed, along with the chitosan, in your bowel movements.

In order to benefit from the fat absorbing properties of chitosan, the supplement must be taken with fatty meals. By doing this, you might prevent about 100 calories of fat per day from being deposited on your body. It all sounds good in theory, but does it work?

As usual, there is a catch. Several weight loss studies were done, mostly on animals, and the results were inconclusive. Therefore, further research on humans needs to be done to evaluate the effectiveness of chitosan as a weight loss supplement.

While it is uncertain if you'll lose weight while taking chitosan diet supplements, there is a good chance you'll experience some gas, bloating, and diarrhea. Also, due to the fat absorbing properties of chitosan, fat soluble vitamins (A, D, E, and K) might not be properly absorbed. Therefore, vitamin supplements need to be taken along with chitosan.

Fortunately, if you want to try chitosan weight loss supplements they are cheap—less than ten dollars a month. (Check current chitosan prices at Amazon.)  But rather than taking diet pills made from crustacean shells, you might be better off eating the critters inside the shells, especially if they are eaten in place of burgers and fries.