This study is a randomized controlled trial. There will be two randomly assigned groups of obese or overweight adolescents (WHO definition). Both groups will be enrolled in a 12 week weight reduction program which includes personal nutritional evaluation and food plan and exercise routine. Follow-up appointments will be held every 3 weeks. One group will be encouraged to update their Facebook status at least once a day, regarding their healthy lifestyle changes (exercise routine, healthy food choice, "checking-in" at the wellness center, kilograms lost, etc). The control group will be asked not to share information about their program on Facebook for 12 weeks. Facebook follow-up will be held by the investigators on the study's Facebook account. Teenagers will be thoroughly explained on how to set the account to a limited profile if they want to. At the end of the program both groups will be compared regarding weight loss and mean BMI.
