Cayenne pepper is a type of chili pepper used to prepare spicy dishes.
The active ingredient in it is called capsaicin, which has been shown to reduce appetite and increase fat burning in many studies (42, 43, 44, 45, 46, 47).
For this reason, it is a common ingredient in many commercial weight loss supplements.
One study found that adding 1 gram of red pepper to meals reduced appetite and increased fat burning in people who did not regularly eat peppers (48).
However, there was no effect in people who were accustomed to eating spicy food, indicating that a tolerance to the effects can build up.