"Everybody is concerned whether there are things we can't see now but will see later," said de la Cruz.
Gastric banding does not lead to the same problems with absorption of essential minerals as bypass surgery. Because of that, bone loss will apparently be less severe with banding. It can still happen because there's less food intake.
"There's still the basic question about whether to do just lap-bands on teens," said de la Cruz-Munoz.
Doctors generally prescribe calcium and Vitamin D supplements after gastric bypass surgery to combat the resulting bone loss -- but patients do not always follow orders.
"About 60 percent of adults are noncompliant, so we have to presume a higher number of adolescents don't take their supplements, either," said Dr. Christine Ren-Fielding, director of the NYU Langone Weight Management Program.
She said calcium supplementation is adequate for overcoming bone loss as long as people take it as indicated.
Some doctors also suggest weight training to help strengthen the bones, but the effects of that are unclear, possibly because adolescents may not comply with that recommendation either.
If bone loss in adolescents continues, experts say there's no other medical treatment for it. Medications like Fosamax, used for osteoporosis, aren't approved for use in children under the age of 18, and it's unclear whether they will work for pre-menopausal women or for men.
Although the study perhaps raises more questions than it answers, some believe they're important ones for the medical community to address.
"Obesity in kids is worse than obesity in adults. The epidemic will be getting worse, so this is something we need to be discussing," said de la Cruz-Munoz.