Review Article Peripheral Signals Mediate the Beneficial Effects of Gastric Surgery in Obesity Silvia Barja-Fernández, 1,2,3 Cintia Folgueira, 1,3,4 Cecilia Castelao, 1,3 Rosaura Leis, 2 Felipe F. Casanueva, 3,5 and Luisa M. Seoane 1,3 1 Grupo Fisiopatolog´ ıa Endocrina, Instituto de Investigaci´ on Sanitaria de Santiago de Compostela (IDIS), Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Traves´ ıa Choupana s/n, 15706 Santiago de Compostela, Spain 2 Departamento de Pediatr´ ıa, Universidad de Santiago de Compostela (USC), Instituto de Investigaci´ on Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Traves´ ıa Choupana s/n, 15706 Santiago de Compostela, Spain 3 CIBER Fisiopatolog´ ıa de la Obesidad y Nutrici´ on, Instituto de Salud Carlos III, Spain 4 Departamento de Fisiolog´ ıa, Centro de Investigaci´ on en Medicina Molecular y Enfermedades Cr´ onicas (CIMUS), Avenida Barcelona s/n, 15782 Santiago de Compostela, Spain 5 Laboratorio de Endocrinolog´ ıa Molecular y Celular, Universidad de Santiago de Compostela (USC), Instituto de Investigaci´ on Sanitaria de Santiago de Compostela (IDIS), Traves´ ıa Choupana s/n, 15706 Santiago de Compostela, Spain Correspondence should be addressed to Luisa M. Seoane; luisamaria.seoane@usc.es Received 24 November 2014; Accepted 21 March 2015 Academic Editor: Takuji Tanaka Copyright © 2015 Silvia Barja-Fern´ andez et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Obesity is nowadays a public health problem both in the industrialized world and developing countries. he diferent treatments to ight against obesity are not very successful with the exception of gastric surgery. he mechanism behind the achievement of this procedure remains unclear although the modiications in the pattern of gastrointestinal hormones production appear to be responsible for the beneicial efect. he gastrointestinal tract has emerged in the last time as an endocrine organ in charge of response to the diferent stimulus related to nutritional status by the modulation of more than 30 signals acting at central level to modulate food intake and body weight. he production of some of these gastric derived signals has been proved to be altered in obesity (ghrelin, CCK, and GLP-1). In fact, bariatric surgery modiies the production of both gastrointestinal and adipose tissue peripheral signals beyond the gut microbiota composition. hrough this paper the main peripheral signals altered in obesity will be reviewed together with their modiications ater bariatric surgery. 1. Introduction Overweight and obesity are serious public health problems in the developed and developing world. It has been estimated that at least 3.4 million people die each year as a result of both disorders [1]. In fact, obesity is considered as an epidemic of the 21st century by the World Health Organization (WHO) due to continued increase over the past decades in the preva- lence of this disorder. In the European Union, obesity afects 10–30% of adults [2] whereas in the USA between 30 and 35% of the general population are obese [3]. Child and youth obesity are particular concern since the National Institutes of WHO has reported that more than 40 million children under the age of 5 years were overweight or obese in 2012 [4]. Children with overweight typically progress to become obese adolescents and adults [5]. According to WHO, more than 700 million adults and children will be obese in 2015 [6]. Obesity is deined as abnormal and excessive fat accu- mulation caused by an imbalance between energy intake and caloric expenditure. his disorder results from the increase of high caloric food intake and reducing physical activity. Moreover, in developing countries malnutrition and nutrient deiciencies coexist with an industrialized proile of lifestyle, characterized by the high energy food ingestion and low physical activity [7, 8]. Hindawi Publishing Corporation Gastroenterology Research and Practice Volume 2015, Article ID 560938, 12 pages http://dx.doi.org/10.1155/2015/560938