Into the wild book How did Chris die?

In the book the reader goes on a literary fatal odyssey just like chris did. The reader however survives yet depressed and pondering. The question is. How did Chris die. How did the book cause this strange effect on the reader and why the author purposely omitted the real reason for his death. Did he poise himself with potato seeds r did he simply stop eating thus fulfilling his real goal of this "fatal" odyssey.