From the smallest biotech to the biggest pharmaceutical stock, The Motley Fool's Market Check-Up covers the health-care sector's biggest headlines, hottest market movers, and Obamacare's ongoing rollout.

In this segment, health-care analyst David Williamson looks at Arena Pharmaceuticals' (NASDAQ:ARNA) deal with partner Eisai to market its obesity drug Belviq worldwide. Shares soared on the news, but could this really be as big of a blockbuster as it seems? David takes a look at the somewhat lackluster sales of both Arena's Belviq and competitor Vivus' (NASDAQ:VVUS) Qsymia, and highlights some headwinds these companies face here, though he also notes several signs that show Eisai remains very optimistic.

Should investors be jumping in or holding off? David gives his thoughts.

Follow David on Twitter @MotleyDavid.