RecruitingClinical trialA Study to See if an iPhone Weight Management App Can Help Promote Weight Loss in Adolescents and Young Adults After a Stem Cell TransplantThis early phase I trial studies how well a behavioral weight loss intervention consisting of a smartphone application and coaching works for the promotion of weight loss in adolescents and young adults after a stem cell transplant. This study may help researchers learn more about how adolescents and young adults can lose weight and develop healthy eating habits.