Weighing a little too much might not kill you, but there’s nothing healthy about it, the head of the nation’s health agency said Thursday, distancing herself from a controversial report suggesting that being overweight isn’t so bad.

Health experts increasingly are faulting a recent study by scientists at the federal Centers for Disease Control and Prevention that concluded obesity is not nearly as dangerous as was thought and that being a little plump might actually lower the risk of death.

At a news conference, CDC chief Dr. Julie Gerberding acknowledged potential flaws in the study and pledged to get scientists and the public back on track.

“It is not OK to be overweight. People need to be fit, they need to have a healthy diet, they need to exercise,” she said. “I’m very sorry for the confusion that these scientific discussions have had.”

Obesity raises the risk of heart disease, some cancers, diabetes and arthritis, and being overweight raises blood pressure and cholesterol, which in turn raise the risk of heart disease, she noted.

The disputed report, published in April, said obesity accounted for a mere 25,814 deaths a year in the United States, vastly lower than the 365,000 deaths estimated just months earlier. Mildly overweight people had a 20 percent lower risk of dying than those who weigh less, it also found.

Many scientists from the Harvard School of Public Health, the American Heart Assn. and the American Cancer Society now reject those conclusions. They say the study’s main flaw is that it included people with health problems ranging from cancer to heart disease, who tend to weigh less because of those problems and therefore make pudgy people look healthy by comparison.