Modern methods of advanced sports nutrition assessment have emerged that can highlight efficient wellness and performance at the time for athletes as well as their coaches. The purpose of this chapter is to cover current methodologies for the measurement of nutritional status and body composition in athletes with an emphasis on practical applications of science. We first talk about the tool that is dietary analysis and why it's important to understand what macronutrients, and micronutrients you are consuming. This section assesses their strengths and weaknesses as well as looking at food diaries, 24-hour dietary recalls, and food frequency questionnaires. Through this data, the tools can help nutritionists in developing individualized diet plans. In part 2, we move on to assess your metabolic rate and continue with a discussion of the use of indirect calorimetry to determine RMR as well as an athlete's total energy expenditure (TEE).