Autophagy, mTor, NAD+, and the immune system are the main factors that make us age.
Our Bodies Lose the Ability to Cleanse Themselves; The fancy term is autophagy
mTOR is a protein that helps regulate cell growth when we are younger, and serves as an important controller of cell metabolism, growth, and survival as we become older
An Essential Protein for Proper Cell Function is Almost Gone by Age 80; NAD+ generally declines gradually, about 4% per year, until it is almost absent in our bodies by age 80.
A Compromised Immune System; a strong immune system helps to keep a person healthy.