Help me? Family crises?

My grand mother has come to live with us. Im a very patient and a VERY understanding person in general. BUT, a few things she does ALWAYS get me confused and annoyed.

Now, I ask her if she wants to eat anything, food, juice, water anything really. She'll insist she doesn't want it, she'll repeatedly say NO no NO no. However, when we are "out of sight" she'll start eating. Now, if we catch her eating, she'll say, "I don't feel like eating".

I dont understand why does she not wanna eat but she "Eats" and "Hides".

EXPLAIN IT PLEASE.

PS: I'm brown, so all the other races if yall are confused please dont respond lmao yall wont get it.