At birth, you had over 270 bones, but some fuse to leave your adult self with just 206! And until you're an adult, your bones just keep growing! Teens and pre-teens need the most calcium -- about 1300 mg, while the average adult needs only 1000 mg to stay osteoporosis-free. If you don't get enough calcium from your diet, your body will leach calcium out of your existing bones for other biological functions like keeping your blood at the right pH, blood clotting and letting cells talk to each other. If there's not enough calcium to go around, you can end up with brittle bones later in life. Eek!

If you need more calcium, get ready to eat! Foods with the most calcium include: dairy products, leafy greens, seafood, legumes and fruit. Plus breakfast cereals, nut milks and other mineral-fortified foods will do the trick. High-impact exercise also strengthens your skeleton because when bones get stressed, they bulk up!

Don't let Osteoporosis take you down or make you weak in the knees.