Do sims gain weight while I play other households?

Hm... perhaps it depends on both the body type and traits? I could always go the easy road, saying that this sim is meant to gain weight (although it is a tad boring that it happens when she is not played). If she stops at the current size, I guess I can live with it, but who knows where she will slow down... I made her pregnant, hoping that will burn some of that extra weight :)