n Wednesday, the Food and Drug Administration (FDA) approved the first prescription diet pill in 13 years, "providing a new option for the roughly one-third of American adults considered obese." The drug — Belviq — is manufactured by Arena Pharmaceuticals of San Diego. Before Belviq, only one prescription medicine, Xenical, had been approved for long-term use in weight loss. "The history of diet pills has been marked by many safety problems, which has made the FDA reluctant to approve new drugs." In clinical trials, those who took Belviq lost, on average, about 6 percent of their body weight in one year. About 22 percent of those treated lost 10 percent of their body weight.