Just to add a thought on the issue of football players dying young. In all areas of life there are people that die young: college professors, pastors, doctors, lawyers, taxi cab drivers, Wal-mart associates, etc., etc. We are more aware when a football player dies young because of the media frenzy. When your local Wal-mart associate dies at the age of 29 there are no cameras, radio shock jocks, or front page coverage.
There are some studies that suggest calorie restriction can increase life. Notice I said suggest because a lot of the studies deal with animal studies or studies of limited scope. Bodybuilders practice a form of calorie restriction. Rather than eating everything and anything they want they carefully plan and monitor what they eat. They only eat enough to meet their physical endeavors of training and their other activities in life.
While it may be true that they eat a lot of calories, in order to stay lean most do not eat EXTRA calories. Contrast this to the way the average person eats, and I would argue they follow a form of calorie restriction.
I would imagine the bodybuilders that cycle bulking phrase where they each what they want and put on a lot of fat and muscle followed by cutting phases could do some damage to their bodies. This is just my personal opinion.
I would think this would only be dangerous when taken to an extreme - not following a clean diet during bulking but following a see-food diet. Considering the physiques bodybuilders have, I would suspect there are few that follow this principle.
Training (just like anything else) when taken to an extreme could be unhealthy. However, the evidence is pretty overwhelming that lifting when done with common sense greatly increase function and can stave off many of ills of aging.
So, does bodybuilding shorten life? I believe bodybuilding could be a double-edged sword. Those that follow sounds principles and train within the framework of common sense should experience a longer life and greater functionality. Those that do extreme, dangerous things could shorten their life.
Eating well, training hard but within reasonable limits, and getting proper rest are all things that can lengthen life and health. I am sure this is the lifestyle of many bodybuilders.