What do you suggest if i am 5'8" and want to grow taller but i am 20 yrs old years old and people keep telling me men stop growing after age 20. is our body not as effective?

Wishful thinking: Unless the family has a tendency toward late growth, most male growth is done by 17-18. Linear growth continues until the growth centers close, (17-18 in most) some will have slower closure of the centers and continue at a slow pace to 20.An x-ray of the wrist and hand can be assessed for growth centers and determine if growh is still possible.