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.

Little is known about the eating behaviors that place adolescents at heightened risk for overweight. In the proposed study, we aim to investigate the role that eating behaviors and genes may play in the development of overweight. Participants will be adolescent girls and boys from a racially/ethnically diverse sample of adolescents from the DC Metro community. Adolescent eating behavior will be observed during laboratory test meals. Adolescents will be provided with a large buffet of foods or a standard meal and instructed to eat until you are no longer hungry. Thirty minutes later, they will taste and rate a variety of highly palatable snack foods. Blood tests will be conducted to examine genes related to eating behavior. Assessments also will include affective states, degree of hunger, degree of fullness, body image satisfaction, disordered eating attitudes and behaviors, and measures of interpersonal interactions.

• INCLUSION CRITERIA:

Volunteers will qualify for participation in the study if they meet the following criteria:

1. <TAB>Age 13-17 years.
2. <TAB>Good general health as indicated by medical history and physical examination.
3. <TAB>Negative urine glucose and normal electrolytes, hepatic, and thyroid function.
4. <TAB>For the fMRI portion only: right handedness (required for standardization of responses).
5. <TAB>For the fMRI portion only: female.
6. <TAB>For the fMRI portion only: overweight (BMI greater than or equal to 85th percentile for age and sex).

EXCLUSION CRITERIA:

Volunteers will be excluded if they have any of the following:

1. <TAB>Medical problem likely to affect caloric intake.
2. <TAB>History of any condition including psychiatric disorders in either child or their responsible parent that in the opinion of the investigators would impede competence to sign consent, interfere with adherence to procedures, or possibly hinder completion of the study.
3. <TAB>Pregnancy.
4. <TAB>Use of medication likely to affect caloric intake.
5. <TAB>History of significant neurological injury or insult.
6. <TAB>For the fMRI portion only: braces (or other metal) that would interfere with the fMRI procedure.
7. <TAB>For the fMRI portion only: non-native English speakers (required for standardization of responses).