Eating Behavior in Children

This study will explore the eating habits of children and determine if eating behavior is linked to genetics. Children between 8 and 17 years of age may be eligible for this study. It will include children who have experienced loss of control over eating, children who report overeating without loss of control, and children who report experiencing neither of the above. Candidates will 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 child sits inside the device for about 5 minutes and the machine determines body fat by measuring air movement. The child 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 child's general health and eating habits. * Acclimatization to test meal conditions for the study. The child is given a yogurt shake to drink and fills out rating scales before and after the drink. Participants will come to the Clinical Center two times at 8:30 a.m. for laboratory meal testing. At each visit, the child will do the following: * In the morning, eat a breakfast of apple juice and a buttered English muffin. * Between 10 a.m. and 2 p.m., pursue activities at the Clinical Center recreation facility or the NIH classroom, but may not eat or drink anything that contains calories. * At 2 p.m., fill out rating scales about his or her hunger level. * At 2:30 p.m., eat from a food buffet that will be made available. * After eating, repeat rating scales about hunger level. The procedure for both visits will be the same, except at one visit the child will be instructed to eat as much as you would eat at a normal meal, and at the other visit, the instruction will be to let yourself go and eat as much as