#6 Cayenne: Researchers at Oxford Polytechnic Institute in England had obese patients add 1 teaspoon of red-pepper sauce to each meal. The study showed that this red-hot herb raised metabolic rates about 25%, which caused their health to use-up more calories. So, if you so comprehensive spicy and hot, you can test this herb with foods to zap fat. Red pepper (cayenne), also improves circulation.