The reason Apple CEO Steve Jobs has been looking like a wraith is due to a mysterious new hormone imbalance that was hard to diagnose but now it has and Jobs expects to fatten up by summer.

Jobs released a statement saying so Monday morning, hours ahead of MacWorld opening, apparently to head off further distracting speculation that he's on his deathbed because his 2004 pancreatic cancer is back.

It's something he could have done when Apple suddenly announced last month that he wasn't going to give his famous keynote at MacWorld, a move - officially attributed to some mumble about it being Apple's last appearance at the IDG show - that simply fed the speculation and depressed Apple's fragile stock price.

The statement also feeds speculation that Jobs, who is widely regarded as being Apple, will step down as CEO this year.

Although he says "I will be the first one to step up and tell our board of directors if I can no longer continue to fulfill my duties as Apple's CEO," he only promises to stick around "during my recovery."

The press - which has been burned before by Apple being less than forthright about Jobs' health - is already agitating for more details than Jobs provided.

The Wall Street Journal, for instance, says, "How serious or benign the problems may be remains difficult to gauge without a fuller, public release of the diagnosis, therapy and prognosis."

Anyway, here is Jobs' full statement:

"Dear Apple Community,

"For the first time in a decade, I'm getting to spend the holiday season with my family, rather than intensely preparing for a Macworld keynote.

"Unfortunately, my decision to have Phil deliver the Macworld keynote set off another flurry of rumors about my health, with some even publishing stories of me on my deathbed.

"I've decided to share something very personal with the Apple community so that we can all relax and enjoy the show tomorrow.

"As many of you know, I have been losing weight throughout 2008. The reason has been a mystery to me and my doctors. A few weeks ago, I decided that getting to the root cause of this and reversing it needed to become my #1 priority.

"Fortunately, 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. Sophisticated blood tests have confirmed this diagnosis.

"The remedy for this nutritional problem is relatively simple and straightforward, and I've already begun treatment. But, just like I didn't lose this much weight and body mass in a week or a month, my doctors expect it will take me until late this spring to regain it. I will continue as Apple's CEO during my recovery.

"I have given more than my all to Apple for the past 11 years now. I will be the first one to step up and tell our board of directors if I can no longer continue to fulfill my duties as Apple's CEO. I hope the Apple community will support me in my recovery and know that I will always put what is best for Apple first.

"So now I've said more than I wanted to say, and all that I am going to say, about this.

"Steve"

Apple then followed with a statement of its own:

"It is widely recognized both inside and outside of Apple that Steve Jobs is one of the most talented and effective CEOs in the world.

"As we have said before, if there ever comes a day when Steve wants to retire or for other reasons cannot continue to fulfill his duties as Apple's CEO, you will know it.

"Apple is very lucky to have Steve as its leader and CEO, and he deserves our complete and unwavering support during his recuperation. He most certainly has that from Apple and its board."

• Steve Jobs Out Until End of June