I no longer menstruate, but as long as I've been on LC boards, I've noticed women concerned that their periods (that's what I call it too - it happens periodically) go wacko when they first begin Atkins. Seems like the consensus is that fat is being released, fat contains hormones and the excess hormones play havoc with cycles. For sure you should still call your doc and check things out, but I wanted to give you some assurance that your situation is not that abnormal. And as far as peri-menopause, Nancy's right, anything can happen.