Omega-3 fatty acids
Omega-3 fatty acids are primarily found in fish, but they are also present in nuts and seeds, flax, and hemp seed oil.
These foods speed up your metabolism because they reduce the production of a hormone called leptin (a natural chemical that slows down your metabolism).
In fact, a study by the Mayo Clinic found that African tribes that included plenty of fish in their diet had five times lower leptin levels than those that did not consume it.