Weight-Loss Pill Fattens Arena Pharma Shares

Arena Pharmaceuticals shares popped Wednesday after the Food and Drug Administration , making it the first new weight-loss drug in 13 years.

Arena CEO Jack Lief described the drug to CNBC’s “Closing Bell.”

“You take one pill in the morning and one pill in the evening and typically patients will lose a significant amount of weight the very first time they go back to the physician for evaluation,” he said.

The drug continues to work over an extended period of time, but Lief said that patients can stop taking it when they reach their weight-loss goal.

Over a third of the U.S. adult population is currently obese, Lief noted, and if nothing is done, it is expected that 42% of the adult population will be obese in a decade. Belviq, the brand name for Arena’s anti-obesity drug, may be an important step in helping Americans slim down, he said.  

— By CNBC.com's Justin Menza.