three grains of rice

When you have no appetite, and feels as though three grains of rice will fill you up; contrasted with "opposite of three grains of rice" where one is ravenous and begins to ask others for their food.

I'm so three grains of rice, I barely made it through that third grain, one more and I'll vom! Or
I'm the opposite of three grains today, are you eating these stale saltines?