Yes I think that's true. It is also mostly decided by how fit/obese you are as young.
Not sure about cells, but fat people are all around us and will never go away.
All of the responses thus far are false. Cell Apoptosis can occur if one remains in a caloric deficit for an extended period of time.
The number of fat cells stays the same they just get larger or smaller depending on your circumstances. Lipo suction will get rid of them though.
Also, on a side note, just recently we learned that new cells in the heart are created. Not so new, but contrary to old thinking, we also have learned that brain cells are not finite and new ones can also be created.
It's called neurogenesis and it is very old news and it is what I got my Ph.D. in.
Do you want a cookie?! Everyone on GB has a Ph.D, so next time restrain yourself from shoving your life story down our throats.