Be very careful about using these. Especially if they're from a multilevel marketing company (direct sales/legal pyramid schemes) - They're usually full of questionable things, bordering on speed or other stimulants, laxatives or it's simply just snake oil.
There's been cases of people on these things that have gotten a false positive result when drug tested at work.
There's no true shortcut asides from surgery, the best you can do is work out and count calories.