Fat cells grow in number (and fat tissue grows as well) by a process called insulin-induced lipohypertrophy, primarily with chronic hyperinsulinemia. This is permanent growth. This process is most obvious in diabetics type 1 who inject insulin in the same spot for years.

This means two things for us. It's very hard to grow fatter when we're lean, it's very easy to grow fat again if we have grown fatter before. That's because it takes time for fat tissue to grow (basically it's the same for all tissues, i.e. muscles, bones, etc), and fat cells can fill up very quickly such as after a meal for example.

As for edema in the legs especially around the ankles and calves, I get that too. I'm sick, I got some infection or something, this is what causes the edema. I didn't get any of that before when I went low-carb and zero-carb after that. It's not a normal effect of going low-carb. On the contrary, going low-carb should cause a loss of water especially in the first few days, that's what I saw too in the first few days. In fact, that's what opponents of low-carb say about it as a way to denigrate low-carb, i.e. "it's not fat, it's water!". Yeah, sure, but 5lbs of water - is 5lbs!