User blog comment:Nobody700/How is he so strong?/@comment-219.65.41.161-20151109131828

Personally ...I think he is like Doomsday from Superman Comics. What if he was created and not born. A test subject who was exposed to the toughest climate and everytime he died, a clone was created from the previous samples DNA, thus recording memory.

In addition maybe during the 3 years he was training, his body was contained in a invisible gravity vortex, which condensed in the first three years and after three years started expanding like a loop. So, every three  years cycle the gravity vortex condenses and then expands around his body, at a slow rate, not sensed even by him.

As a result, his body when he walks, talks, drinks, breathes or laugh is going through minimal yet gradually increasing stress and at the same time is getting acclamitized. Others might not sense it strongly as it is in close proximity of Saitama. However, this dense vortex makes his day to day activity like a intense workout, so the 3 years of dedicated workout would be like superhuman training.