Soda
-Carbonation has been linked to increased incidence of bone density loss. This means becoming closer to having osteoporosis. This may be caused by decreased intake of calcium by soda drinkers or by the carbonation changing the pH status of the body causing increased utilization of calcium and phosphate to act as a buffer taking those key elements out of the bones.
-Sugar in excess can lead to diabetes. This you probably know. But drinking fluids with high sugar in excess causes larger insulin spikes more often which encourages the development of diabetes. Excess sugar also encourages cavities to grow in your teeth.
-Diet soda is not better. It may actually be worse. In order to make something "diet" or "calorie-free" you have to use many toxic chemicals to strip the ingredients and these chemicals are still left around for you to ingest. Things like aspartame (that are carcinogenic) are in these diet sodas. Your body retains sodium and therefore retains water to compensate for the toxins placed in it by consuming these diet sodas. People typically report gaining weight with diet sodas as compared with dropping soda all together.
-Soda is filling and it fills you with useless calories. You are less likely to drink water or intake enough calcium if you are drinking sodas than you are if you do not. You are not actually physiologically less thirsty after drinking a soda because it is not hydrating you, but you think you are less thirsty and are not encouraged to down a bottle of water. This is dangerous and can leave you chronically dehydrated. This causes skin problems and aging as well as puts a lot of stress on your organs.
- Soda consumption across the world has been linked in research trials to obesity and weight gain, especially in children.
Juice
-Sugar in drinks is still sugar consumed. Basically the same problem as with soda: you drink empty calories not contributing to your nutrition.
-100% fruit juice IS NOT 100% the fruit you are buying. Those crafty marketers! What this means is that everything in the bottle came from a fruit or veggie, but not necessarily the one whose flavor you just purchased. Let me explain. The thing you are buying is diluted with much more sugary and sweet juices like grape or pear to make the product cheaper. Check the ingredients on the back of the bottle to see what you are getting.
Looking for alternative drinks? Try the green smoothies that list their natural ingredients or buy your own. Make sure to check the list of ingredients on anything you are buying. Try tea or coffee instead of soda.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1829363/