Vitamin B is a good source to speed up your metabolism. You can get vitamin B through food sources such as bananas, potatoes, chili peppers and lentils. May I add also that you need to eat low fat longevity foods. The key here is to eat in moderation, my friend Christopher Guerriero once told me that I need to eat low fat longevity foods like salmon almonds, red grapes, blueberries, garlic, spinach and whole grains