Steve Jobs, after months of concern about his health and weight loss, said he is suffering from a nutritional ailment and that he plans to remain Apple Inc's chief executive officer during his treatment.

"I have been losing weight throughout 2008. The reason has been a mystery to me and my doctors," Jobs, who turns 54 in February, said yesterday in a statement. "After further testing, my doctors think they have found the cause - a hormone imbalance that has been robbing me of the proteins my body needs to be healthy."

Jobs' decision to talk about his health, which prompted Apple shares to rise as much as 6 percent, caps months of speculation by investors that his health was deteriorating and that he may have to hand the CEO job to Chief Operating Officer Tim Cook. Jobs, who had successful surgery for a form of pancreatic cancer in 2004, turned Apple into a consumer-electronics juggernaut with the iPod and iPhone.