I was expecting to lose weight with chemo, not gain weight! I am frequently hungry as well. Sometimes I wake up in the morning and my stomach is killing me it's so hungry. I have tried drinking diet soda or flavored water when I am hungry and between meals. It seems to me that sometimes it's not that I am hungry but rather thirsty.
I am a lifetime weight watchers member but I stopped when I was diagnosed. The one thing that I still try to do is to figure out my food for the day in the morning including snacks. Then I try to stick with it even when I'm hungry.
Eating foods high in fiber helps a lot too. They help you feel fuller longer.
Most important though, you are on a tough journey and treats along the way help a lot to keep your eye on the end in sight and give you the strength to keep fighting.