I had the same problem with one of my dogs too, but didn't want to switch brands because its the only food he can eat. So, I just lowered his food intake. He doesn't seem to mind/notice and its working for him. A dog never needs anywhere near as much of a premium food (such as Eagle Pack) as they do a low quality food (Eukanuba). Premium foods are much more filling. Winston used to eat 2 cups (twice a day) of Nutro and now he eats 1 1/3 cups (twice daily) of California Natural.

If your dog as always had weight issues, you may want to get her checked for a Thyroid condition, but I'd just try dropping the amount of food given for now and see what happens. Please, please do not switch back to Euk. It really won't benefit your dog at all.