Why Did My Vision Go Monochrome?

Firstly, I have no pre-existing condition that I know of which would cause this. Basically, I hadn t eaten in awhile. A few days, I mean. I walked into the kitchen to speak with my father, and suddenly I felt terribly confused and couldn t make out words. I went to go make some food, and slowly all of the colours around me began to dull. Yellows turned into slightly off-whites, reds turned to a mix of grey and red, and everything just kept turning more and more monochrome. I stood and stared for a moment, shook it off, and then went into the living-room and my vision restored itself (I hadn t eaten still). Why might have this have happened? I have gone longer without eating before and this has not once happened to me.