Diet pills: Vivus, Arena and Orexigen in race to market safe weight-loss drugs

On NBC's hit series The Biggest Loser, obese contestants must huff and puff through weeks of endless push-ups, sit-ups and treadmill sprints in hopes of shedding more pounds than their rivals. But with all the sweat and tears required to go from fat to fabulous, many other plus-sized people are holding out for a safe diet pill that could get the same jaw-dropping results without all the effort.

Now, there may finally be some real options on the horizon. Arena Pharmaceuticals (ARNA) said Tuesday a late-stage trial of lorcaserin shows its experimental obesity drug improves patients' body composition such as body mass index and waist circumference. Meanwhile, rivals Vivus (VVUS) and Orexigen Therapeutics (OREX) are developing similar drugs. All three are racing to be the first to provide a safe drug that really works in a market potentially worth billions of dollars.