Jobs was diagnosed with pancreatic cancer in 2004 and underwent surgery, CNNMoney.com reported Monday. Recently, his weight loss has been visible to the public, causing concern the cancer had returned.

In a letter made public Monday, Jobs said a hormone imbalance had been "robbing me of the proteins my body needs to be healthy."

A remedy for the problem was "simple and straightforward," Jobs wrote "and I've already begun treatment."

He said he expected to regain his weight by late spring.

In the meantime, "I will continue as Apple's CEO during my recovery," he wrote.