This is not normal. This could be due to a medical condition or an emotional issue.
There are some medical conditions that cause people to overeat without much regard to what they are eating or what the consequences may be. From the way you describe this, it would seem to be a fairly new condition with your daughter. I would take her to a doctor to rule out anything organic.
If it is emotional, something may have happened to cause her to try to gain weight in an attempt to become unattractive or to try to find comfort in eating.
Either way, your daughter needs your unconditional love and support at this time. Good luck!