Most of my runs I don't really need to worry about fueling, just water. This summer was exceptionally hot and dry, so I brought water on almost every run. And that's OK with me; my pack gives extra room for carrying my phone and camera, keys, etc..
However, with all the longer runs I have been doing recently, fueling has been essential.
It's just not going to be pretty if you are running all day on the trails and don't have anything to keep you going.
I believe sugar is essential (carb), though some might prefer to add fats or protein to fuel with. The bottom line is that you need SOMETHING out there.. Figuring what the right combination of "something" is- that part can be tricky.
My personal observation is that in a race where you expect to run the whole thing without using the restroom (big potty, here!), it's best done on strictly non-fiber carbs (gels, sports drinks, beans, chews, etc..). This is best for races under 5-6 hours.
Fiber and protein (i.e. bars, meat sticks, trail butter, real food), these things are known to cause "big potty". They also redirect your blood from elsewhere in the body to your stomach for digestion, and will lead to a stop or two in many people's races. They also, however, provide energy to keep a runner going longer and that is why ultra runners must have them if they are running for hours on end. (Only going on research here, since my longest run ever was not quite 6 hours).
After running out of some prepackaged bars, I decided that my 5 hour runs would need some alternative fuel, and I went to the kitchen to see what I could whip up.
A sports drink, tasting like a non-alcoholic margarita, made from Agave syrup ( maybe 1/4 cup in a 20 oz bottle of water), a couple of True Lime packets, and some table salt to taste (electrolyte replacement).
It worked beautifully over a 4+ hour run with lots of climbing (over 5000 ft). I didn't have any solids until about an hour from the end, when I ate 6 peanut MnMs. I drank both bottles because it was a hot day, and had no bathroom stops on that run. (I think I sweated most of it out.)
A few weeks later I tried the same concoction with good result on a longer run (over 5 hours) with just a little less climbing.
A second fuel experiment involved solids. I expected to be out for over 5 hours on my last run and did not want anything too bulky, but I knew a little more substance might be needed. I don't like the idea of eating a sandwich with bread and fitting it in my pack, so I dropped the bread out of a PBJ and made a couple of PBJ pouches.
The ratio I used was 1:1 for PB and homemade jam: 2 big spoons of PB, 2 big spoons of apricot jam, placed inside of a baggie and smushed to make a sweet combo. Throw in a little salt, and it is good to go.
I made two pouches and started about 40 minutes into my run with some. To eat it, I just bit a hole in the corner of the baggie and squeezed some in my mouth. Then, I tucked the open corner in the middle and wrapped the rest of the pouch around it to make sure it didn't ooze all over my vest pack.
This was repeated again later in my run, until the bag was empty.
All I took to drink during this run was water, which was really all I needed. The PB concoction made me thirsty, and I was well hydrated and fueled.
Between the two experiments, I think I have a new 50k formula ready to go.I may be lucky with an iron stomach! I'm definitely not an expert and can't give you a carb /protein count, but it worked for me!
How about you? What do you fuel with?
Have you ever tried making your own sports drink or using "real" food? What were your results?