There are also problems from drinking only water too, especially if you are doing really prolonged heavy physical stuff in very hot and humid conditions.
The tendency of pundits is to recommend very high intakes of water very frequently... before you get thirsty, so body has enough water to process things.
What that does bad is several things. All those large doses of water flush away minerals from your bloodstream pronto. That leaves you without enough electrolytes to function. When you are in the middle of heavy physically demanding stuff in hot weather, you can have energy crash or even organ failure.
Another thing that is possible is too much water in these hot/humid conditions coupled with heavy prolonged exertion, can cause the brain tissue to swell really bad. Of course, this is serious, sometimes fatal results of death.
This happens all the time in military where you have to make a very long road march with a very heavy rucksack (like 30 kg or more) and move out at a fast pace in very hot and humid weather. Many military leaders in this case will tell you to keep drinking water like crazy. You are in a catch-21. You do not keep drinking lots of water, you will lose it all through sweat and breath. You take all this large amount of water, you flush out your minerals and electrolytes, you lose energy, you risk organ failure, and if you keep up the heavy water drinking and keep moving with such a load, you will pass out, perhaps die.
That is why it is important for one to know one's energy, nutrition, hydration, and mineral status and take effective care.
In the case of the long road march, many Armies have long ago discovered that adding a little salt to the water works, along with slow carb supplements, like oatmeal bars with a little sugar carbs and salt, do an effective job at keeping the electrolyte levels high enough to function if done properly.
Too much sugar intake with these chems in energy drinks under the hot/humid conditions with heavy workout are also a recipe for failure as well. If one drinks at LEAST one volume of water for that energy drink, one could likely get by with drinking one or two of those energy drinks in a day of heavy activity and not die, but why take chances? There are plenty of electrolytes, minerals, and energy (both fast glucose carbs and slow burn carbs) in food we eat with our mouths.
If we can be aware of our levels discussed above, we can balance energy/hydration/mineral intake and keep ourselves safe and ready for action WITHOUT energy drinks.
What a lot of do is not plan ahead and since these energy drinks are a lot more available in more places than proper food and take zero preparation, many wind up with the junk food and drinks. There is nothing wrong with one of those if there is enough water consumed, it is done at right time and there is also other nutrition involved. I bring a sports drink to venue all the time as it taste good and can get me by if I use it right and balance out everything effective according to my body's levels and physical demands at the time.
