One example of a fat blocker is Chitosan, which is derived from exoskeleton of curstaceans (shrimp, crabs, etc), which claims to be able to block 6 to 10 times its weight in fat. However, unmodified chitosan would only remove around 10 calories of fat per day from your diet. Modified Chitosan may live up to this claim, but there are concerns that it would also remove important nutrients and minerals from the food that you eat.

Chitosan is also used as a growth enhancer in gardens, and perhaps that is where it should stay.