NPR's Planet Money had a great story on this: http://www.npr.org/blogs/money/2013/01/18/169719749/episode-431-a-billion-dollar-bet-against-weight-loss-shakes ht

NPR's Planet Money had a great story on this: http://www.npr.org/blogs/money/2013/01/18/169719749/episode-431-a-billion-dollar-bet-against-weight-loss-shakes http://www.npr.org/blogs/money/2013/01/18/169719749/episode-... Agree though that there is a difference between a pyramid scheme (Herbalife imo) and a fad (Groupon) though they have similar growth trajectories. There are lots of startups that could arguably be considered fads e.g. snapchat, it's yet to be seen whether or not it's a novelty or solving a basic human interaction problem as Facebook did.