Keep testing ammonia and nitrite every day. Right now the other test results don't matter. Every time ammonia or nitrite is not 0 do a 75% water change. I'm afraid your nitrite is going to start going up soon.
Until the ammonia and nitrite are both at 0 without doing a water change I personally would only feed sparingly once every 2 or 3 days. Ammonia is far more harmful to fish than lack of food as mentioned in the link @Colin_T posted above. Once that is sorted you can look at getting their weight up.
Here is another useful link that explains what we mean by cycling http://www.fishforums.net/index.php?/topic/421488-cycling-your-new-fresh-water-tank-read-this-first. Obviously as you already have fish in there you can't use the fishless method.
Until the ammonia and nitrite are both at 0 without doing a water change I personally would only feed sparingly once every 2 or 3 days. Ammonia is far more harmful to fish than lack of food as mentioned in the link @Colin_T posted above. Once that is sorted you can look at getting their weight up.
Here is another useful link that explains what we mean by cycling http://www.fishforums.net/index.php?/topic/421488-cycling-your-new-fresh-water-tank-read-this-first. Obviously as you already have fish in there you can't use the fishless method.