Chromium is said to help mobilize fat. Some say to use it in conjunction with L-carnitine.
I've tried some of these weight loss methods and while they may work short-term, long-term the attrition rate is pretty high and the results are poor.
I would strongly recommend diet and exercise for weight loss. Dr Beckerman has some helpful tips in his blog.
I was also pretty surprised to hear of some of the consequences of diet pills, etc.
Dr Beckerman shared some of these in a post.
The data on chromium isn't great. Although there are aspects of it that seemed promising, the research does not sugest a significant association with weight loss.