My best friend always used flat Cokacola [sp] and plain salted crisps.
As a 'recoverying' anorexic I have a huge list: because once I go off food I can't eat or drink anything

mixed bags of fruit and nuts to nibble
bananas - slow release energy
pancakes - mixture keeps a couple of days in the fridge
Dextrose tablets to stave off nausea
Very thin Readybrek
Milk shakes cold from the fridge
Spoonful of Bovril in hot water and toast - as I begin to recover appetite I add already boiled rice into the mug and sometimes frozen peas
Dry crackers
DH cooks thinly sliced chicken breasts with plain rice
Those bread sticks can help too …...