Does undereating affect milk supply

we're going through tough time. my baby boy came early, he's in the NICU and we're skating by on the bills so I haven't been eating much.... will this affect the content of my milk? I notice i'm very thirsty so I try to drink as much water as possible but since baby's arrived I've had more fast food to cut corners between time and money. normally I wouldnt eat so bad but these weeks have just been rougher than the usual.

edit: my supply is okay for now. I eat about twice a day and still take vitamins