This preface discusses how the manual aims to provide both foundational nutritional science knowledge (Unit 1) and practical application knowledge for working with clients (Unit 2). It acknowledges that some foundational information may not seem immediately relevant but emphasizes that students do not know what career paths they may pursue in the future. The preface also highlights various learning tools provided in the manual like chapter objectives, summaries, key terms, case studies and references to help students learn and review the material. The overall goal is to train students to be highly knowledgeable fitness professionals who can deliver outstanding results for clients.