Every diet book implores you not to begin any diet without first consulting, then proceeding under the supervision of a physician. This is excellent advice. First, we who write diet books don't want to get sued for gazillions of dollars if you drop dead two days into the diet, whatever the reason. But seriously, you're about to put your body through a significant period of organic stress and it's wise to make sure you're up to it. Further, doctors are in the business of maintaining the human body, and explaining your goals and plans to somebody who's seen it all before many times is well worth the time and money of a visit to the doc.
I'll be honest and admit I didn't follow my own advice here. Doctors... brrrrrr ... can't stand 'em. But please do the reasonable thing: as I say, not as I did.
Important. If you've been, or think you may have been exposed to toxic chemicals such as pesticides, defoliants, or industrial chemicals, don't begin this or any other diet without consulting a doctor. Toxic chemicals accumulate in fat cells and cause no harm as long as they're immured there, but if you rapidly lose weight they can be released faster than your body can dispose of them and can lead to serious problems. Fortunately, most hackers have been exposed only to tetchy computers and flaky software which rot the mind, not the flesh.