Arena Pharmaceuticals (NASDAQ:ARNA) and VIVUS (NASDAQ:VVUS) are the epitome of water-cooler stocks. Every American knows that our country is dealing with an obesity epidemic, so what could be more of a "sure thing" stock than companies behind weight management pills that are clinically proven to work? If it sounds to good to be true, it's because it is.

In the following video, health care bureau chief Brenton Flynn provides a brief overview for those who are new to the Arena Pharmaceuticals story. Specifically, he discusses why a partnership that Arena entered into means that its drug, Belviq, needs to become much more than a blockbuster drug to provide shareholders with the profits they're looking for.

Brenton Flynn has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.