Increases in adipocyte number occur via repliction of preadipocytes, a process that is not restricted to infancy but occurs throughout life. In contrast to still widely-held beliefs, mature fat cells can be eliminated by dedifferentiation or apoptosis.
This is from the link:
Fettgewebe und Fettsucht
Adipose tissue and obesity
Now, I'm not sure what eliminated by dedifferentiation or apoptosis.
means exactly but it certainly sounds like die and go away?
Also from the previous link I posted:
John Prins: Well what we have done in our laboratory here in Brisbane and also in Cambridge in the UK, was we've demonstrated that human fat cells have the ability to die in simple terms.
So individual cells can die at any stage of life, and probably do so all the time, and the fat cells in our body are in a state of turnover, much as our muscle cells are and our liver cells are, and so at any stage of life, we have the ability to either create new fat cells if we're in a state of having more energy into the body than is leaving the body, so if we eat more than we require; but equally we have the potential to lose fat cells in the reverse situation.
Here is a quote from a very good article on the subject of fat cells
Studies conducted in Sweden in the1970s were the first to show that fat cell numbers could be reduced.2 The re~searchers followed obese patients over a seven-to-nine-year period and discovered that some lost weight while others gained bodyfat. They noted that the decreases in bodyfat among the obese patients who lost weight over the long term couldn't be ex~plained by a reduction in the size of the existing fat cells. Those patients had actually lost adipose cells, a reduction that closely correlated to the change in bodyfat. In other words, they lost weight not because each fat cell got smaller, but because they got rid of a substantial number of fat cells.
This one is not scientific but makes a good read:
And while I am at it - the presently accepted cellular level belief of HOW one loses weight when there is less food than needed to sustain its present size (AKA dieting) is that first the contents of the cell are used up - going for uses elsewhere--whether it be brain function or energy etc. The contents are replaced with fluid. Then a certain point comes and the fluidy replacement gets whooshed out and the entire cell gets reabsorbed.
That comes very close to the "when you are not losing the pounds you are losing the inches--not quite--but close)
That brings us to a past urban myth about fat cells never die--they just shrink and sit there like hungry vultures, waiting to refill themselves and make you an enormous balloon once more. Well that one was disproved some time ago.
I think in conclusion it is safe to say that current scientific opinion is that if fat cells sit around empty for long enough they will die and be re-aborbed.