This photo provided by Food and Drug Administration shows Arena Pharmaceutical's anti-obesity pill Belviq. The Food and Drug Administration has approved Belviq, the first new prescription drug for long-term weight loss to enter the U.S. market in over a decade. The agency cleared the pill Wednesday for adults who are obese or are overweight with at least one medical complication, such as diabetes or high cholesterol. (AP Photo/Food and Drug Administration)

For the first time in 13 years the US Food and Drug Administration has approved a pill to help people lose weight.

The approval by the US federal regulator comes almost two years after it first rejected it on safety concerns.