You'll need both to protect your bones. Calcium is the most important nutrient in a teenager's diet, but it's not the only one, so a balanced diet is essential. Health professionals often talk about what effect poor eating habits will have later, but solid nutrition practices are important now.
Growth occurs during adolescence.
Teens who eat poorly could become puny adults. And an inadequate diet could lead to poor school performance, weak bones, a lack of energy and disease. Doctors talk about eating right to prevent disease later. That's happening now. It's not waiting until they are 40.