Several types of natural fiber to help decrease your appetite satiate effect.
The most used is the glucomannan. Taken with water, produces a thick gel in the stomach, reducing the feeling of emptiness. It is not digestible, so it does not add any calories. Another substance to lose fat is guarana, caffeine-rich, active metabolism of fats and stimulating effect on the body.
It is also used chitosan, polymer extracted from marine crustaceans that attacks the stomach preventing fat absorption and eliminating them with feces. Must be constant to takes effect.