- Size (pretty much self explanatory) - Insertions

Insertions is pretty much the shape and placement of muscles, some people have their biceps higher up in their arms, some lower down. Some people have mis-aligned abs some have perfect abs.

Zyzz, though nowhere near of being the biggest, had what most would call perfect or very aesthetic insertions.

His muscles' shape and placements were closer to some kind of perfect anime character than that of the average bodybuilder / gym goer.

This is one of the reasons, along with his personality, why he got so famous.

The documentary touches on mental illness, but it is needlessly vague, as anyone familiar with the subject's mental illness would have recognized it within a couple minutes of watching, at most, confirmed at the mention towards the end of the subject's deep anxiety. I suspect it is more common among body builders than the general population, as the culture seems to encourage it.

The mental illness, once thought to be uncommon, has an accurate, poetic, yet unfortunate name, one perceived to be pugilistic. It affects successful individuals, football quarterbacks, captains of industry, and presidents. Better it was called "mental illness x452" or something harmless, but instead it is called narcissistic personality disorder. Other than the deep anxiety, NPD itself hardly affects the sufferer except through how it affects others in the life of the subject, and from social feedback, hurt leads to hurt. One doesn't need to be a narcissist to be confident, but there is such a thing as overconfidence, arrogance.

It is tragic, in the original sense of the word, that Zyzz died so young. It is not explicitly stated, but I suspect heart failure could have been due to an enlarged heart, which is not all that uncommon among body builders. My understanding is it occurs due to focusing on anaerobic exercise, which weight lifting is, and not also or not executing enough aerobic exercise, like swimming, running and calisthenics. As the heart gets larger, the heart chambers get smaller, pumping less blood and less oxygen, in the right circumstance leading to heart failure and death.