There are three ways of running, and carrying a bit of kit and food. Only one really allows you to run, the others let you trot or jog.
The first way is to get a good kangaroo pocketed water-proof cagoule, and stick a few ounces of Carb powder in a plastic bag, ready for mixing in stream water. This is wrapped round your waist, and tied. If the Cag is nicely big, you can get away with not having gloves, on days that are not too cold. You should be able to go an awful long way like this. It’s the best way, the freest, and the fastest.
The second way is with a light belt with a pocket and a Bottle, there are lots of types, some obviously better than others. If you are not really carrying much, you still might need the bottle for where you cant get water. If it is really hot, a big lad might need a litre an hour. Some people cant wear a belt because it interferes with lower lung breathing, but if you wear it lower than you think you should, you might change your mind.
The third method is to carry a light sac. These running sacs go from two litres, to around twenty, and some of them do their job really well. Often people choose a sac because they like a bladder to drink from. There are a few downsides to bladders however. The first is that bladders are hard to clean, and you can easily get sick. Second they are hard to fill and take time to fill. Third you get all the Carb at the start, and just a weaker solution later, this can really screw up your energy calculations.
I love the first way, but normally go for a belt with two triangular or square bottles, which are more stable than round ones. If I really am going for an un supported long jaunt, I go for the smallest sac I can get my stuff into. Even if carrying a bladder I still carry a little bottle to get into a water source for filling. My lightest two bottle rig, is 350grs with 2x750cc bottles, it is home made. I have Two litre sacs, 5 litre sacs, and 15 litres, they are all very light and stable.