You can further expand this to other "foods" (apologies for calling Soda a food...):
Foods that provide an acidic response in the body can contribute to bone loss. Do a search for "body pH" and you'll find lots of books that discuss this. The essence is: your body NEEDS to be slightly alkaline, for health reasons. When you consume a food that gives an acidic response (and the list is long...) the your body WILL neutralize it, as a very high priority metabolic issue. If necessary, it will take calcium and other minerals from...guess...yes, your bones, to neutralize said acid. Rinse and repeat often enough, and you get bone density issues.
Good news: quite reversible for you, as youth is on your side. Cut out the acidic drinks / foods, keep lifting (heavy) weights to stimulate further bone growth, and get your essential nutrients up (minerals AND vitamins).
Here's a source for information on healthy foods - it's a great free site with excellent information. I pre-searched for their tips on "osteoporosis" problems. Here's the summary of their recommendations:
"A healthy diet can prevent or mitigate the damage caused by osteoporosis."
- Organically grown fruits and green leafy vegetables;
- Dairy products (if you don?t have sensitivity to milk products);
- Cold water fish (September 8, 2003)
*Avoid coffee, soft drinks, refined sugar and excess salt".
The information is worth a read IMHO. Don't look there if you like pizza and coke though, it's not yet made the "healthiest foods list...". Good luck to you!