Teen body image issues can often enough be solved with time or fitness. Society is evolving into needing immediate gratification for everything. The microwave makes it quick to heat food. The Internet makes it quick to research. The cell phone makes it quick to socialize. Teens often just don't want to wait for the results they desire. Teaching them how to change their own bodies through hard work and dedication is a much healthier alternative both for their body and their mind.
If an adult wants to get cosmetic surgery, weighs the risks and rewards, and determines it to be worth it for their career, self-esteem, etc. That is their choice. Teenagers struggle with body issues and learning a sense of confidence and comfort with imperfection is an important part of growing up. Thus teenagers with body image issues need to let their bodies mature and learn to accept some of who they are.
See, this is one of the real ills of society. Firstly, we have an obesity epidemic that should be addressed immediately. Secondly, there is an image that teens seem to want to live up to. This has to be done away with somehow and remedied. It's a very dangerous path.
I hate it when adults go this route, so I am absolutely against it when it comes to children. There is no reason to let a child use cosmetic surgery to correct body image issues. They should be forced to wait until they are legally able to choose for themselves. So many people grow out of their teenage body issues that it's better to wait.