[DocSanae]

Some things I learned in med school.

With childhood obesity, the NUMBER of your fat cells increase and plump you up.
With adult onset obesity, the SIZE of your fat cells increase and plump you up.
There is a limit to the size the fat cells can attain, but unfortunately, there is no limit to the number of fat cells that increase, so beware of child-onset obesity.

Fat cells are what save you in times of famine, though.

[CraigT]

this is opposite of what I was told. I was led to believe that the # of fat cells were set at birth, and we only inceased their size.

Interesting.

[DocSanae]

Well, yes, there is a set limit actually, to the number of fat cells you can develop, but as with many things during your growth period, you don't start out with the full number, you develop into it, or rather, your life style will direct the development. So, if you stayed within the normal weight range during your growing up years, the number of fat cells you have, is not up to the maximum, and it will stay that way. When you start gaining weight thereafter, each cell gets fatter, while the number stays the same. This is thought to be the major reason why ppl who were plump throughout their childhood have a tougher time controlling their weight, than those who were relatively fit during their youth.
At least, that's what our lecturer on the subject of obesity and weight control told us.