I've heard that it acts as an appetite suppressant and it makes you not crave sugar that much. I recommend L-Caritine, it promotes lean muscle mass and it re-directs your fat intake and converts it into energy. Just do an internet search on it and you can read more about it.
Using chromium picolinate alone will probably do you no good. In fact it's just wasting money(although most chromium products come very cheap). I recommend you take a daily muti-mineral/vitamin. Almost all of them have the ingredient chromium picolinate. If your looking for a diet pill then that's a whole different ball game because there are so many out there.
L-Carntine is used mostly by athletes and bodybuilders. It acts as a non-essential amino acid carnitine. It helps metabalize food into energy. It is not an appetite suppressant.