BOSTON—The Florida Keys diet, which can be adequately described in 14 words, has been padded into a 204-page book: Losing Weight The Florida Keys Way, available in bookstores Tuesday. "The diet is pretty much, 'Avoid saturated fats and simple carbohydrates, eat mostly fresh vegetables and seafood, and exercise," said author Dr. Harris Jegen. "Unfortunately, no one is going to shell out $24.95 for one sentence, so I've got some recipes and charts in there, a bunch of testimonials, and a 50-page Diet Diary." Jegen's previous books include The Florida Keys Diet and The Florida Keys Diet Made Easy.