A lot of people have food allergies to gluten, which is in OATS, wheat, barley, spelt, & kamut. One of the side effects of these allergies is cravings and binge eating on them. It stems from the fact that cooked grains were not in our natural diet and we haven't developed the enzyme to break down the gluten...(same thing with the enzyme caesin in pasteurized dairy). Over time this can lead to celiac disease, chrons disease, and other medical problems.
Another problem she may have is candida. It's an intestinal imbalance between good and bad bacteria, in which the bad bacteria way outnumber the good guys. They are able to feed and live in very unstable conditions and LOVE sugar. This is any kind of Sugar whether it be refined Sugar or those found in carbs. It can definetly leave massive cravings for sugar/carbs. I used to have severe candida and I would have such bad cravings for pretzels and bagels. Now I have cut them out, almost a year ago, and I do not ever have cravings for them anymore!!!