Introduction: Obsession with thinness and body dissatisfaction can lead adolescents to follow unsupervised diets, which could result in risky weight control behaviors such as fasting, vomiting, use of diuretics and laxatives. The aim of the current study is to examine weight control behaviors in dieting adolescents and relate them to body dissatisfaction (BD) and obsession with thinness (OT). Methods: A cross-sectional study was conducted on 439 adolescents from Valparaiso public schools to investigate risky weight control behaviors due to BD and OT scales from the Eating Disorders Inventory-2 (EDI-2), comparing restrained eaters and non-restrained eaters. Results: A total of 43% adolescents had followed a weight loss diet without medical supervision. The dieters had higher BD and OT values. Moderate to severe food restriction, based on expert judgment, was observed in 29.6%, and differences in the presence and severity of purging behaviors were found between the 2 groups. Conclusions: One third of the adolescents studied followed diets without professional supervision and had higher BD and OT values, as well as risky weight control behaviors. Overweight and obese adolescents followed more restrictive diets and developed riskier weight control behaviors. (C) 2015 Sociedad Chilena de Pediatria. Published by Elsevier Espana, S.L.U.