Eating disorders are a growing health problem among adolescents and have increasingly become the focus of studies due to their prevalence. Both obesity and anorexia nervosa are associated maladaptive eating behaviours that may be relevant to development. With this case report, it is intended to discuss the diagnosis and management of a female adolescent patient, diagnosed with obesity and attention deficit-hyperactivity disorder (ADHD). A 16-year-old, female, obese adolescent was referred to our in-patient clinic due to maladaptive eating styles, depressive symptoms and ADHD symptoms. Her early course of illness, diagnostic process, treatment and short-term outcome are described. At the time of discharge, the patient's Clinical Global Impression (CGI) scale severity item score was 2 (borderline mentally ill) and CGI improvement item score was 2 (much improved). We report the present case with the purpose of establishing a pediatric approach to obesity, a disease not included in Diagnostic and Statistical Manual-5 under eating disorders, yet we believe it shares common underlying genetic and environmental causes.