This research studies the energy balance behaviors (usual eating, physical activity, sedentary) and non-shared experiences of siblings discordant for weight (one sibling is lean the other is overweight).

This research studies the energy balance behaviors (usual eating, physical activity, sedentary) and non-shared experiences of siblings discordant for weight (one sibling is lean the other is overweight). To accomplish this, siblings attend four laboratory sessions where they consume one of two types of kool-aid, smell the pizza, or rest quietly. Siblings then eat a dinner meal. Siblings also wear an activity monitor for one week and record their physical activity and sedentary activities in a habit book.

Inclusion Criteria:

• between 13-17 years old
• Have discordant same gender sibling (one is below 70th percentile, one is above 85th percentile
• Speak/read English
• Moderate or greater liking of study foods

Exclusion Criteria:

• No current diagnosis of a psychiatric or eating disorder.
• No dieting, dietary restrictions, or allergies that would interfere with study participation.
• No medications or conditions that could influence taste or appetite.
• No health concern or physical disability that would limit participation in physical activity.
• No endocrine or central nervous system disorder that could produce overweight.
• No current use of tobacco or nicotine products by the adolescent siblings.

Forty-eight sibling pairs (24 pairs of boys and 24 pairs of girls, 96 total adolescents) age 13 to 17 years who are discordant for overweight/obesity will be studied to assess potentially modifiable non-shared experiences within and outside the family environment that alter energy balance behaviors and contribute to adolescent overweight. We will also measure the height and weight of up to 3 of their best friends.