It's a day that Arena Pharmaceuticals investors have long, long waited for: Obesity drug Belviq is now on the market. 

The company had a seemingly endless wait for DEA scheduling, ultimately receiving class 4 status. In the meantime, competitor VIVUS got its obesity drug Qsymia approved and into patients' hands. 

In this video, health-care analyst David Williamson checks in on the obesity-drug wars, where things stand between Arena and VIVUS, and what Arena investors should look out for given some of Qsymia's initial challenges.