You'd need to eat alot of paprika, cayenne etc for it to aid your metabolism enough to matter, however, spices make otherwise bland food much more interesting. Probably 70% of my meals are spicy now. In fact, pretty much everything except breakfast has some sort of spice in it. Remember spicy doesn't just mean curry. Loads of west Indian foods are spicy, and of course Mexican food, and even some Chinese, Spanish & Italian foods as well.