I have been wondering the same thing, I'm here in Connecticut. It's been a weird fall. I'm still feeding them a little cool weather food daily, it has been in the 50's during the day, and around freezing at night. Tomorrow will cool down more, highs of 40's for the rest of the week, so I think I might stop feeding them. The pond is small, only 5' x 8', and with no vegetation and no bugs there isn't anything for them to eat.
Maybe some people who don't feed their fish have bigger ponds? I do know I was advised last year to only feed them once every three days or so in the warm months, and the fish hardly grew at all. This year after reading so many comments about fish needing to be fed daily I did so, and my fish grew by leaps and bounds. So much so that one of my "goldfish" grew big enough so that I learned he's actually a Koi.