EXAMINING TRAJECTORIES OF 24H MOVEMENT BEHAVIOR COMPOSITIONS TO UNDERSTAND WEIGHT STATUS CHANGES DURING ADOLESCENT DEVELOPMENT - PROJECT SUMMARY/ABSTRACT NEARLY A THIRD OF YOUTH IN THE U.S. EXPERIENCE OVERWEIGHT OR OBESITY (OWOB). IF CURRENT TRENDS PERSIST, AN ADDITIONAL 3.41 MILLION ADOLESCENTS WILL HAVE OWOB BY 2050, TOTALING APPROXIMATELY 43.1 MILLION AND AFFECTING AN ESTIMATED 57 PERCENT OF U.S. ADOLESCENTS. THIS ALARMING PROJECTION HIGHLIGHTS THE URGENT NEED FOR INNOVATIVE, EVIDENCE-BASED PUBLIC HEALTH STRATEGIES TO ADDRESS THE RISING RATES OF OWOB DURING ADOLESCENCE. INCREASINGLY UNHEALTHY LIFESTYLES HAVE CONTRIBUTED TO THIS PUBLIC HEALTH CRISIS, WITH EVIDENCE SUGGESTING THAT POPULATION PATTERNS OF DECREASING PHYSICAL ACTIVITY (PA), INCREASING SEDENTARY BEHAVIOR (SB) AND INSUFFICIENT SLEEP HAVE CONTRIBUTED TO ADOLESCENT OWOB. YET, EXAMINING EACH BEHAVIOR IN ISOLATION PROVIDES AN INCOMPLETE PICTURE, AS THESE BEHAVIORS ARE CO-DEPENDENT AND COLLECTIVELY INFLUENCE HEALTH, KNOWN AS THE 24H MOVEMENT PARADIGM. WHILE RECENT RESEARCH THAT HAS ADOPTED THE 24H PARADIGM HAS SHOWN ASSOCIATIONS BETWEEN MOVEMENT BEHAVIORS AND WEIGHT STATUS, EXISTING STUDIES ARE LIMITED BY CROSS-SECTIONAL DESIGNS, RELIANCE ON SELF-REPORTS, AND SIMPLIFIED GUIDELINE-BASED ANALYSES. LEVERAGING THE ADOLESCENT BRAIN COGNITIVE DEVELOPMENT (ABCD) STUDY'S COMPREHENSIVE LONGITUDINAL DATASET INVOLVING DEVICE-ASSESSED MOVEMENT BEHAVIOR DATA, THIS PROJECT PROVIDES A UNIQUE OPPORTUNITY TO ADDRESS CRITICAL KNOWLEDGE GAPS REGARDING THE COMPLEX INTERPLAY BETWEEN 24H MOVEMENT BEHAVIORS AND WEIGHT STATUS USING COMPOSITIONAL DATA ANALYSIS DURING ADOLESCENT DEVELOPMENT, POTENTIALLY SHAPING TARGETED OWOB PREVENTION EFFORTS. THIS F31 PROJECT HAS TWO SPECIFIC AIMS: (1) IDENTIFY DISTINCT PATTERNS IN TRAJECTORIES OF 24H MOVEMENT BEHAVIOR COMPOSITIONS ACROSS ADOLESCENT DEVELOPMENT, DETERMINE SALIENT FACTORS THAT PREDICT TRAJECTORIES, AND EXAMINE HOW MEMBERSHIP IN THESE TRAJECTORIES IS ASSOCIATED WITH WEIGHT STATUS INDICATORS, AND (2) DETERMINE WHICH 24H MOVEMENT BEHAVIOR(S) CONFER THE GREATEST INFLUENCE ON FACILITATING OR PREVENTING EXCESS WEIGHT DURING ADOLESCENT DEVELOPMENT AND EXAMINE THE IMPACT OF REALLOCATING TIME BETWEEN THESE BEHAVIORS ON WEIGHT STATUS. ALIGNED WITH THE NIDDK 2025 STRATEGIC GOAL #1, THIS RESEARCH ADDRESSES THE PRESSING NEED TO UNDERSTAND BEHAVIORAL FACTORS THAT IMPACT OBESITY. BY ADOPTING THE 24H MOVEMENT PARADIGM, THIS RESEARCH AIMS TO DEEPEN UNDERSTANDING OF HOW MOVEMENT BEHAVIORS IMPACT ADOLESCENT OBESITY, A LEADING CONTRIBUTOR TO FUTURE CHRONIC DISEASE. INVESTING IN ADOLESCENT HEALTH PAYS TRIPLE DIVIDENDS: IT IMPROVES CURRENT HEALTH AND WELL-BEING, SUPPORTS HEALTHIER TRAJECTORIES INTO ADULTHOOD, AND ENHANCES THE HEALTH OF THE NEXT GENERATION. THE RESULTS OF THIS RESEARCH WILL CONTRIBUTE TO IDENTIFYING CRITICAL PERIODS AND BEHAVIORAL PATTERNS ASSOCIATED WITH WEIGHT GAIN DURING THIS KEY DEVELOPMENTAL STAGE. SUCH FINDINGS WILL PROVIDE ACTIONABLE INSIGHTS THAT CAN GUIDE NATIONAL POLICIES AIMED AT ADDRESSING OWOB AND INFORM THE DESIGN OF TARGETED, TIME-SENSITIVE INTERVENTIONS FOCUSED ON BEHAVIORS MOST STRONGLY INFLUENCING WEIGHT DURING ADOLESCENCE. BY ADVANCING KNOWLEDGE OF THESE RELATIONSHIPS, THIS WORK WILL HELP IDENTIFY AND SUPPORT ADOLESCENTS AT GREATEST RISK FOR OWOB AND PROVIDE A FOUNDATION FOR PREVENTIVE BEHAVIORAL INTERVENTIONS TO IMPROVE HEALTH OUTCOMES.