What causes the weight gain?

I have recently been diagnosed with Stage III infiltrating ductal carcinoma.  Both the surgeon and the oncologist say my tumor (approximately 10 cm. in a small breast)is too large to be operable at this time and must be shrunk first with chemo and radiation.  My oncologist has given me a choice between Adriamycin (AC?)and CMF.  At this point, Taxotere, tamoxifen, Taxol, etc are not being considered in my case.
What is it that causes weight gain in so many breast cancer patients who receive chemo?  And how much weight is usually gained?  Is this gain permanent or does it go away after treatment?  Why is it that so many breast cancer patients gain weight from chemo, while people with other types of tumors, even though they may be on the same chemo protocols have trouble maintaining their weight?
Thanks.

[CCF-RN,MSN-JS]

Dear Shantimarie, The chemotherapy treatments that have been recommended for you do not usually have weight gain as a side effect.  Some of the weight gain may be due to chemotherapy bringing on menopause and the changes associated with that stage of life.  You may find you

[Jemina]

I was told I might put on weight and I began to.  I think because I felt less atractive sfter surgery and was less mobile. Once I realised this I started to excercise more ( but moderately) eg walking briskly and watched my diet eating more healthily. I have not put on weight since and even lost a pound or two.
Good luck!