Fit for Christ or Gluttons for God? An Overview of Research on Religion and Body Mass 11 Terrence D. Hill, Samantha M. Galindo, and Amy M. Burdette Introduction Over the past three decades, numerous studies have shown that religious involvement – indicated by observable identities, feelings, beliefs, activities, and experiences in relation to a spiritual, divine, or supernatural entity – is associated with better health across the life course. This general pattern has been remarkably consistent across indicators of health behavior (e.- g., drinking and smoking), mental health (e.g., depression and anxiety), physical health (e.g., disability and allostatic load), and all-cause and cause-specific mortality risk (Burdette et al., 2018; Ellison & Levin, 1998; George et al., 2002; Hill et al., 2011, 2016; Idler, 2004, 2011; Koenig et al., 2012; Krause & Hayward, 2016). In contrast to these more established literatures, sur- prisingly little attention has been devoted to body mass and related outcomes (e.g., body image and eating disorders). As obesity rates continue to rise in various subpopulations of the United States (Hales et al., 2020; Ogden et al., 2020; Zhang et al., 2020), the health sciences should prioritize research on understudied social determinants. Religion is clearly understudied and, more importantly, often associated with greater body mass across a range of populations (Koenig et al., 2012; Yeary et al., 2017). Understanding this unique risk profile is one way to advance the social epidemiology of body mass and religion and health research, which tends to over- emphasize the ways in which religion might pro- mote population health. T. D. Hill (*) · S. M. Galindo Department of Sociology, The University of Texas at San Antonio, San Antonio, TX, USA e-mail: terrence.hill@utsa.edu A. M. Burdette Professor of Sociology and an Associate of the Pepper Institute on Aging and Public Policy, Florida State University, Tallahassee, FL, USA # Springer Nature Switzerland AG 2022 G. Garcia-Alexander, D. L. Poston, Jr. (eds.), International Handbook of the Demography of Obesity, International Handbooks of Population 12, https://doi.org/10.1007/978-3-031-10936-2_11 187 In this chapter, we provide an overview of the religion and body mass literature. Along the way, we consider (1) the nature and extent of the association between religion and body mass in population-based studies of adults conducted in the United States and other countries, (2) explanations for why religion might be associated with body mass, (3) subgroup variations in the association between religion and body mass, and (4) several important avenues for future research. Although we intend for this collection of studies to be representative of the field, we do not consider it to be exhaustive. The general aim of this review is to update and extend previous reviews (Koenig et al., 2012; Yeary et al., 2017) and to spark greater attention to this important area of body mass research.