The internet is not a great place to buy weight loss foods (with a few exceptions). It's an even worse place to buy supplements and a terrible place to buy prescription drugs (but that is a whole other story).
The problem is that there is still very little risk to rip-off artists online. They are free to promise miracles and deliver nothing more than a placebo with a fancy label. The FDA is powerless to stop such marketing unless the products make medical claims and even then the agency is so short-staffed that weight loss scams are a very low priority. If there is a safety concern, then the FDA will act very quickly as it did with "Hydroxycut" a few years ago when evidence emerged that the product could cause liver damage, but normally the responsibility to police false advertising falls to the Federal Trade Commission (FTC) and they too are understaffed. All of this means that many totally ineffective weight loss products are sold online, fly "under the radar", never receive scrutiny and remain on the market for years.
So let the buyer beware. Better still, don't buy.