NUTRITION AND PHYSIOLOGICAL FUNCTION: Edited by Labros S. Sidossis and Annemie M.W. ScholsBody composition phenotypes and obesity paradoxPrado, Carla M.a; Gonzalez, M. Cristinab; Heymsfield, Steven B.cAuthor Information aDepartment of Agricultural, Food and Nutritional Science, University of AB, Edmonton, Alberta, Canada bPost Graduate Program in Health and Behavior, Catholic University of Pelotas, Pelotas, RS, Brazil cPennington Biomedical Research Center, Baton Rouge, Los Angeles, USA Correspondence to Carla M. Prado, PhD, Alberta Institute for Human Nutrition, Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-002 Li Ka Shing Centre, Edmonton, AB T6G 2P5, Canada. E-mail: [email protected] Current Opinion in Clinical Nutrition and Metabolic Care: November 2015 - Volume 18 - Issue 6 - p 535-551 doi: 10.1097/MCO.0000000000000216 Buy Metrics Abstract Purpose of review The obesity paradox is a highly controversial concept that may be attributed to methodological limitations related to its identification. One of the primary concerns is the use of BMI to define obesity. This index does not differentiate lean versus adipose tissue compartments (i.e. body composition) confounding health consequences for morbidity and mortality, especially in clinical populations. This review will describe the past year's evidence on the obesity paradox phenomenon, primarily focusing on the role of abnormal body composition phenotypes in explaining the controversies observed in the literature. Recent findings In spite of the substantial number of articles investigating the obesity paradox phenomenon, less than 10% used a direct measure of body composition and when included, it was not fully explored (only adipose tissue compartment evaluated). When lean tissue or muscle mass is taken into account, the general finding is that a high BMI has no protective effect in the presence of low muscle mass and that it is the latter that associates with poor prognosis. Summary In view of the body composition variability of patients with identical BMI, it is unreasonable to rely solely on this index to identify obesity. The consequences of a potential insubstantial obesity paradox are mixed messages related to patient-related prognostication. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.