Hi Tabitha,
I don't want to give you false hope but in my case it was much longer than 7-10 days before I saw any "big difference". In fact, it was more like 6 weeks before I saw any difference at all! The radiation effects continued to build for at leat 3 weeks post treatment. I ultimately lost 60 lbs., got down to 109 (my wife tells me I look like Ghandi). I am up to 115lbs now. It took a very long time to turn around the weight loss. Dehydration can be a serious problem and you must watch it very closely normal fluid intake should be around 2-3 liters a day. I still wonder if I would have been better served with a feeding tube.
I eat ice cream almost every day (by doctors orders). I also supplemented the Carnation instant breakfast with a milk shake to keep the calories up.