Thermogenic supplements are those that may help slightly increase the metabolism for a few hours after you take them, thus resulting in the body burning more calories even when at rest. Fat-burning supplements aren't necessarily all thermogenic, as some supplements with this label affect fat metabolism by limiting the amount of fat that gets absorbed rather than causing it to be burned more quickly.
Thermogenic supplements are one of the most common types of weight-loss supplements. These include ma huang and bitter orange extract. Supplements that are sometimes used as fat burners include chromium, carnitine, caffeine, conjugated linoleic acid, green tea, kelp, forskolin, fucoxanthin and capsaicin.