Identified in Mice Fat is eating us alive, at least in the developed world. Too many fat cells and the medical problems they can drag in their wake make obesity a leading cause of death in America. Controlling that door has long been the Holy Grail of obesity research, and while Hotamisligil says we are still a long way from having a working key, his lab has discovered what he believes to be a genetic lock, two genes that control the extent of differentiation from adipose stem cells into fat cells.
Mammals have two general classes of fat cell, brown and white.
It is our white adipose cells that haunt us after the holidays. They engorge themselves with fat, storing excess energy as triglycerides and releasing them as free fatty acids to cover caloric deficiencies. The two GATA genes downregulate white adipocyte differentiation. Only in extreme conditions can you add to this pool. For adults, we have no concrete figures, but the available evidence indicates that the number of cells that can become adipocytes is more or less constant unless you are exposed to extreme conditions.