SyphonX said:
Soda dehydrates you. Especially cola anyway. People need to realize this. Soda is nothing but sugar and syrups, and neither help hydration in any possible way. It's like saying alcohol hydrates you.
People seem to think it "magically hydrates" because they get a 'feeling' when drinking it. This is simply sugar entering the bloodstream and the small high you get from receptors in your brain indicating you are quenching an addiction. Soda is high in caffeine and all sorts of (weapons-grade sugars, as I like to call them) that will get you addicted.
Try running a mile after only drinking soda for a few days, see how fast you nearly pass out. Also, try it in the heat, and then tell me soda is =/= water for hydration.
Soda is over 90% water. The sugar content has no bearing whatsoever on the thirst issue. Nor does the carbon dioxide.
Soda in general contains less caffeine than most other caffeinated beverages. Caffeine is not some "magically dehydrating" compound - it acts like a mild diuretic, increasing the rate at which the kidneys extract water from the bloodstream. Tolerance to caffeine develops rapidly, which reduces the magnitude of this diuretic effect. Never mind the fact that in desert heat, the primary route of water loss is sweat, not urine.
Realistically, the soda would quench thirst, but reduce the amount of time it takes you to become thirsty again. It would definitely not make you even thirstier. It's not like sea water, which is so salty that it takes more water to excrete the excess salts than you get by drinking it, and which actually does make you thirstier as a result.
After all, alcohol is a much stronger diuretic than caffeine, yet until about the 19th century alcoholic beverages were people's primary source of hydration due to the general lack of clean drinking water.