How much more food and water?

Water is totally dependent on what the local water sources are like. That varies so wildly between localitites and timeframes that the only worthwhile answers would be from those who hike exactly where you hike, and when you hike.

As for how much more food... summer hiking generally requires less food than winter hiking, although this also depends a lot on daily mileage and other factors.

That much said, I usually take about 3200 calories per day, which for me weights about 26 oz. per day. That is for hiking about 10 miles a day in summer, in mountainous terrain, with approx. 2000 feet of elevation gain on an average day (elevation loss is not so important).

I usually start at the trailhead with at least a liter of water, even if I expect good water availability. Quite often I will carry closer to two liters, just for the sake of not needing to think about water for the first several hours. In waterless conditions, this amount can go up considerably.