7. Drinking More Will Only Serve To Dehydrate You More
There's a part of our brain that inaccurately equates drinking liquids of all kinds with battling dehydration, but that's not really how our bodies work. We require a constant intake of water to survive, and without it, we dehydrate and die within a period of about three days.
Drinking only soda may seem like you're keeping yourself from dehydrating, but sadly, Coke and Pepsi may cool you down on a hot day, but they aren't going to give your body the water it needs, and it's all thanks to caffeine. Caffeine is a natural diuretic, and it works to make your body get rid of fluid through urine.
This often happens before your body has a chance to use it, so if you drink nothing but soda, you'll find that you urinate far more than you did with water. That's your body telling you that it's eliminating fluids and needs to have them replaced with plain H2O, or you're going enter a world of pain.
The first symptom you'll feel from dehydration will likely be a massive headache. This will be followed by fatigue and constipation. It is possible to survive on the water found in Coke and Pepsi alone, but you'll need to consume far more than normal, just to get the minimal amount of water your body requires.