How Munchery Works
How FreshDirect Works
There are a few that appear to be mildly effective. This includes Caffeine, Green Tea and Glucomannan (a fiber that can reduce appetite). However, the results are usually weak and inconsistent and certainly nothing to get excited about. At the end of the day, the only thing that is really proven to help you lose weight is changing your diet.
Exercise can help too, but what you eat is by far the most important.