- Insulin. The amount of piling evidence we see for neurodegenerative and various auto immune disorders linked to insulin resistance should caution everyone especially with age to really keep an eye on this stuff. Fasting insulin (not BG), A1C, and proper implementation of carbohydrates is probably something most guys should keep into consideration.
-Genetics. Sure genetics load the gun and lifestyle pulls the trigger, but some people's guns are like cannons while others have a BB gun epigenome. I have unfortunately seen this in both sides of my family; one is thankfully almost bulletproof while the other not so much.
-Moderation. This lifestyle is anything but that. But sadly the more you push the envelope, the more the engine adds wear and tear before giving out. And that's life in general. People in very high stress jobs aren't living the longest.
Bodybuilding is perhaps COMPLETELY antithetical to longevity (and this is my opinion, feel free to disagree). All the things that drive oxidation, and aging: insulin levels, free radical production, telomere shortening are fueled by high calorie diets (often linked with digestive issues for years), steroid use in very high physiological doses, heavy brutal training, and sleep issues (primarily due to sleep apnea that most guys ignore for years and years).
But all of us are fortunate enough to learn, and discuss this stuff so we cant do our best to prevent the side effects (more apropos term here) of this lifestyle. And be big and as healthy as one can manage at the same time.