When I swam in HS, I was super hungry, too, but not so healthy. We were told to eat as many healthy calories as possible (I could never eat the amount recommended by our coach even with all of the junk food I ate). Also, since your dd is young, don't skip out on the healthy carbohydrates; they are what make brains function and give energy.
I have seen sports drinks at the HFS that do not include corn syrup. My dh recommends Lucozade (sp?) because it is supposed to be a better balance of minerals and sugars to hydrate. I like the flavored SmartWater with electrolytes in it. Again, in HS, we were told to dilute gartorade because the sugar conccentration was to high and would cause dehydration... this was over 12 years ago, though, so maybe they have improved their formula.