The National Academies Roundtable on Obesity Solutions hosted a public workshop series in April and June 2023 that explored the current science on measures of body composition and body fat distribution. Discussions focused on the strengths and limitations, and clinical and anthropological perspectives of body mass index (BMI) as a measure of adiposity and health. Presentations also shed light on the connection between misinformation and bias and stigma, as well as challenged current communication strategies to improve messaging about obesity. Table of Contents Front Matter 1 Introduction 2 Obesity: Definitions and Perspectives 3 Tensions and Perspectives Around BMI 4 Applications and Uses of BMI, Body Composition, and Body Fat Distribution 5 Looking Ahead 6 Communicating How Obesity Is Defined and Diagnosed 7 Innovations in Communicating About Body Weight in the Clinic and Beyond 8 Ethics and Trust in Communicating About the Intersection of Body Weight and Health 9 Improving Communication About Body Weight 10 Promoting Change in Culture and Perception About Body Weight References Appendix A: Workshop Agendas Appendix B: Biographical Sketches of Workshop Speakers and Planning Committee Members