Stress can strip our appetites for sure. Maybe try to eat something neutral when you can because your body does need fuel. I hope once you start treatment the new (temporary) normal of the routine of it settles your nerves a bit. The steroids will make you hungry, don't worry on that front. And I get that it's hard to let go of caring about the exterior, I gained weight with chemo, but it is hopefully just a few months, you can get through it. I know chemo is scary and unpleasant but it is medicine, it does work. And it will be less scary in some ways once you start.