Hoodia products don't contain hoodia. They often contain fiber that swells to mimic a full feeling, and charge 100x the value of the fiber. They may also contain various mystery ingredients. But we know that they don't contain genuine hoodia gordonii because it isn't yet available in this country and probably won't be until next year. The patent to the product is owned by Phytopharm and export of hoodia gordonii is protected by African law.
In the meantime, it's perfectly legal to sell product that claim they contain hoodia even though they don't, simply because of the lack of government regulations in the industry.
As far as hoodia goes, as kaplods mentioned it is used
occasionally by hunters going off on long trips without much food, and not as a weight loss tool. Results have only been seen when eating a 4 inch chunk of fresh hoodia gordonii which contains a special molecule, patented as P57, which is what affects the appetite.
There are also a lot of types of hoodia which are legally sold here, but only the hoodia gordonii contains P57 and you can't get it. So you're out luck no matter what.
Unilever has partnered with the company that owns the patent to P57 and hope to have genuine and effective hoodia products on the market either this year or next. It's still undergoing safety testing.
When the real thing is available for purchase, we plan to spread the word