Eating Behavior in Adolescents

This study will explore the eating habits of adolescents and determine if eating behavior is linked to genetics. Healthy adolescents between 13 and 17 years of age may be eligible for this study. Candidates come to the NIH Clinical Center at 8:00 AM to be screened with the following: * Medical history and brief physical examination, including height, weight, and body fat measurements. Body fat is measured using a device called a Bod Pod. The adolescent sits inside the device for about 5 minutes and the machine determines body fat by measuring air movement. The adolescent must wear a tight-fitting swimsuit for this test. * Urine test to look for sugar or protein in the urine and to test for pregnancy in females. * Blood tests for routine chemistries and for gene studies related to eating behaviors. * Questionnaires and interviews about the adolescent s general health and eating habits. * Acclimatization to test meal conditions for the study. The adolescent is given a breakfast shake to drink. Participants come to the NIH Clinical Center at 10:30 AM for laboratory meal testing. At this visit, the adolescent does the following: * Eats food from a buffet of everyday foods that most kids eat. * Fills out questionnaires. * Tastes and rates the flavor of a variety of snack foods.