 9. Quality control: The investigators involved in this study have completed a training program on the methodology and data acquisition procedures. Each of them have a procedure manual that detailed the administration of the questionnaires, operation of the UTU, measurements of the anthropometric indexes, along with collecting and handling the blood specimens. The same doctor and machine of ultrasound is used during the whole study. All collected data will be registered and treated with the Epidata software version 3.1. 