I have heard rumors that she had diabetes. Apparently her mom said she did, but it has not been confirmed.
It could possibly be the reason. There is an eating disorder among people with Type 1 diabetes known as diabulimia. Diabulimia is when people with Type 1 purposefully do not take their insulin, or do not take the right amount, in order to lose weight. It is extremely dangers as blood sugar that is too high (and if you are losing weight due to high blood sugar it is too high) leads to a condition known as diabeticketoacidosis (DKA) in which the body starts attacking itself for fuel because it is not getting any fuel from the glucose in the blood. The blood literally becomes acidic and if left untreated it can be fatal. Plus, high blood sugar damages a lot of internal organs and women in particular are at a much higher risk of heart disease. I'm not saying this is the case (I'm not even for sure that she did have diabetes), but it is a possibility of those reports are accurate.