Do you gain fat cells?

I thought that after puberty the number of fat cells in your body was determined. As you gain weight in adulthood the fat cells just increase in size until the lipids start to spill out into your blood. Am I right?

Fat cells do swell up, but I think the number of cells increases as well.  Adipose tissue invades your viscera, resulting in that dangerous abdominal fat, and I think to do that the cells would have to increase in number...

The cells increase in size to a certain amount, but if you keep gaining beyond that they do divide, and you wind up with a larger number of cells. 

Yes as you gain weight through life, the fat cells will increase in number.  

When you lose weight the stored fat in the cells is used for energy but the extra fat cells remain.  (Ready to store fat again if given the chance!)

no no no....your fat cells never go away and you never gain any...they just shrink or expand.

vmcbutterfly is right - after some cursory internet research, it looks like fat cells don't divide/multiply after puberty.  They just grow or shrink.

link to article in howstuffworks about fat cells

it's true that adipose cells never go away and shrink and expand, but like the other posters says, when they reach a certain big size, they will divide, and you'll be stuck with the news as well.

Or so that is what my cell metabolism professor told us :-)

That makes sense, bluegirl.  Adipose cells probably have their DNA programmed to make them split when they reach a certain size.

Here's an abstract that confirms this.

"1. Adipose tissue mass is dependent on both the average volume and the number of its constituent adipocytes. Significant alteration in body mass involves alteration in both adipocyte volume and number. 2. Increases in adipocyte number occur via replication and differentiation of preadipocytes, a process which occurs throughout life. Decreases in adipocyte number occur via preadipocyte and adipocyte apoptosis, and possibly adipocyte dedifferentiation. 3. Overall regulation of adipose mass involves endocrine, paracrine and possibly autocrine systems...[..] 4. In adipose tissue, known molecular regulators of adipose cell number...[...] effect a concerted alteration in adipocyte volume and number. This review largely focuses on the control of fat cell acquisition and loss and the influence of these processes on adipose tissue mass and regional distribution."

Research shows that once fat cells triple in size they divide.  You have to be super obese to reach this point.  Think of the people in  the Brookhaven Obesity Clinic.  This can also happen to women who gain over 100 pounds while pregnant.  Most people don't have to worry about this, even if you are obese.

nods

so if fats cells multiply when they get too big, how much percentage in weight do you have to gain to create new ones?

Original Post by helpless:

so if fats cells multiply when they get too big, how much percentage in weight do you have to gain to create new ones?

Good question. I'm trying to find that answer right now, though the percentage in weight is likely different for each person. Knowing the percentage body fat may give a better answer.

In other words, a 5'2" 170 woman will likely hit that "dividing" point sooner than a 6'2" 170 man, even if they both double their weight.