Cells grow in number, but not in size. Cells are always very small since they must retain a high surface area to volume ratio.
Your growth is cell growth (and cell division).
uses up food and oxygen more quicklyhas more trouble moving enough materials across its cell membraneplaces more demands on its DNA
Im not a "religious freak" but I do believe in God as well as science. God created scientific laws and he created our boundaries. His reasons for doing such are beyond our comprehension.
Somatic cells (regular cells) and gametes (sex cells) all grow in number through mitosis (for somatic cells) and meiosis (for gametes)