Capsaicin, which is found in red chilli peppers (used to make Paprika and other similar spices) has been found to reduce appetite and increase the metabolism.

 

The study done in India found that Capsaicin controls the gene that lowers appetite and increases the metabolism by stimulating brown adipose tissue to lose energy as heat.

 

Capsaicin also altered micros in the gut, so they metabolism (e.g. used) more fat.

 

Taken from Nutritional Biochemistry, May 2, 2014