While a substantial body of research suggests that RRV is related to obesity, there is very little research on factors that contribute to the RRV of food, particularly how patterns of eating can increase or decrease the motivation to eat specific foods. Previous work has demonstrated that a subset of individuals with obesity show increases in RRV of food after repeated consumption of large portions of high energy density (HED) snack foods, which has been conceptualized as sensitization. Preliminary data suggest that sensitization of the RRV of HED food is a predictor of weight gain over time. However, more work needs to be done to address this relationship using a planned, prospective study design, using adolescent research subjects, and examining potential moderators of this relationship.

The purpose of this study is to identify risk and protective factors to excess zBMI change in adolescents over time. Aim 1 was to measure the relative reinforcing value (RRV) of a preferred HED and low energy density (LED) snack food before and after 2-weeks of daily exposure. Aim 2 was to assess the RRV of exercise and sedentary activity. Hypotheses include 1) sensitization to HED food will be associated with greater zBMI at the time of testing as well as greater zBMI change over time 2) sensitization to LED food will be associated with lower zBMI at the time of testing in adolescents and less zBMI change over time. 3) Greater RRV of exercise will be protective against zBMI increases over time.

Inclusion Criteria:

• between 12-14yoa (male and female)
• zBMI: -1.5 to +2.0 (*determined by Height/weight measurement at Visit 1)
• neutral or higher liking of the study foods
• Willingness to complete 9 study visits over 2 years.

Exclusion Criteria:

• -metabolic or endocrine disorder
• use of medications known to effect appetite (Ritalin, Adderall, Concerta, Wellbutrin, Prednisone, etc)
• Unwilling to complete the study visits
• allergy to study foods
• dislike of study foods (*determined via Preference for Study foods forms at Visit 1)
• parent report that child reads below 4th grade reading level
• parent report that child cannot complete light physical activity without assistance
• No English Speaking parent or legal guardian (therefore cannot provide consent in English nor answer questionnaires for this study) * all other exclusion criteria are assessed from Survey monkey screening in advance of the first appointment vis parental report. At the first appointment the child is directly asses for height, weight, and The linking of study foods.

Adolescents living in the Western New York area, aged 12-14 years at the time of enrollment. Flyers were posted in the community within a 30 min drive of UB South Campus. Additionally, flyers were sent to list serves, posted on facebook, and distributed to both private and public schools within a 40 min drive of the university campus.

Participants with complete baseline data were included in this analysis

Through study completion up to 24 months.

We used the standard definitions of adverse events.