It becomes a vicious cycle and the more simple carbohydrates
you eat, the worse it gets and can/will lead to Type II diabetes.
Insulin is often considered the "fat storage hormone", because whatever sugar you consume is shuttled, by insulin, into fat cells, if it's not used right away for energy.
I'm not real "up" on PCOS, but it's caused by cysts on the ovaries.
Both insulin and PCOS can cause weight gain and/or make it, seemingly, impossible to lose.