Heh, I pushed a few million dollars with of Garcinia here in the US via online retail using alarming ad copy, such as "SHOCKER: 1 Weird Tip That Melts Nasty Body Fat!". You guys may have seen it.
The money was great for my employers (not me), but we all knew the stuff didn't work. Ditto for other stuff Oz pushed, like Green Coffee Bean, Raspberry Ketone, and so forth.
The trick is to advise the nutrient to be part of a "diet system". Most folks tend to tighten up their diet anyway when they start over with a new drug or supplement, so they really have no idea what's working and what isn't.
The last trick is to make sure the user "feels" something. Green Coffee Bean was excellent for this, because it's a natural stimulant. Didn't do a damn thing for you, but psychologically, the fact that people "felt it working." You may be witness to the same phenomenon with intra workout supplements--it's all bullshit.
Moral of the story is to save your money. If you want a real fat burner, look into T3, pharm GH, and/or Clenbuterol. Weigh the risks.
Believe me, if a natural product caused radical weight loss on its own, it would rock the entire world. Fads are just that: make believe solutions to a personal, serious problem a lot of people will pay to believe it'll help them without effort.
It's all marketing.