Meer dan het Uiterlijk: Een Integratief en Longitudinaal Perspectief op Identiteit en het Lichaam bij Adolescenten en Opkomende Volwassenen

Despite the central importance of body satisfaction to psychological well-being, surprisingly little research has examined the interplay between body image and identity development. Identity development is one of the key tasks of adolescence and emerging adulthood, and theoretical and empirical work has long suggested that identity and the body are intricately linked. Erikson (1968) emphasized that feeling at home in one's body is essential for achieving a coherent identity. More recently, scholars have conceptualized the adolescent body as a primary 'identity project' (Kling et al., 2018). During this period, young people undergo profound physical and social changes while simultaneously navigating increasing sociocultural pressures related to appearance. This convergence may lead to heightened body awareness and susceptibility to internalizing appearance ideals as a means of shaping identity. Since many young people fall short of these ideals, body dissatisfaction becomes highly prevalent, increasing the risk of psychopathology such as eating disorder (ED) symptoms. Although identity formation and body image are both considered central to adolescent development, research in these areas has largely evolved in isolation. Moreover, body image studies have traditionally concentrated on negative body evaluations, overlooking more adaptive and embodied ways of relating to the body. In response to recent calls in the literature, this dissertation takes a holistic approach to bodily experiences. It integrates negative and positive body image, as well as the broader concept of embodiment. Embodiment refers to the subjective experience of inhabiting one's body and includes elements such as body connection, functionality, and agency (Piran, 2016). This dissertation primarily aims to broaden our understanding of the interplay between identity and the body among community adolescents and emerging adults. To this end, the dissertation examines the complex relationship between identity and the body using a multidimensional, developmentally informed approach. Identity functioning is evaluated using multiple complementary approaches, including identity synthesis and confusion, identity processes, and identity statuses and trajectories. The bodily experience is addressed through body image and embodiment. By including both female and male participants, the research addresses a significant gap in the literature, which primarily focuses on females. Part I (Chapters 1 and 2) of this dissertation focuses on the interplay between identity formation and indicators of negative and positive body image. Additional attention is given to their associations with ED symptoms. Chapter 1 uses a person-centered approach to explore the developmental links between identity formation and body image. The results reveal distinct identity pathways related to the differential development of body image, psychological processes related to the body, and ED symptoms. Chapter 2 confirms the longitudinal interplay between identity, body image, and ED symptoms. It focuses on the directionality of effects and identifies internalization of appearance ideals as a key underlying mechanism. Part II (Chapters 3 and 4) takes a more differentiated and holistic approach to the body, examining the concept of embodiment. Chapter 3 illustrates the intricate cross-sectional relationship between identity formation and embodiment. Chapter 4 confirms this interplay longitudinally, focusing on co-development and the directionality of effects. Finally, Part III (Chapter 5) examines ED symptoms and eating competence, demonstrating how interindividual differences in eating behaviors are shaped by individual and contextual factors. These aims are achieved through the use of a combination of variable- and person-centered analytical strategies. This approach provides a thorough understanding of the relationship between identity and the body during adolescence and emerging adulthood. The findings have significant implications for developmental theory, prevention efforts, and clinical practice; and underscore the importance of fostering adaptive identity development and positive embodiment in young individuals.