If you are (or want to be) an athletic/fitness minded person who is following the most current and reliable information possible, here are the consensus organizations for both exercise and nutrition. ACSM began as a collection of MDs and exercise physiologists who set out to integrate the most current and relevant health and performance evidence available and establish an authoritative body for exercise science.
Similarly, the ISSN is a coalition of nutrition scientists, educators and practitioners who recognized a specific need for athlete-focused eating guidance that supported and led the industry for new research in the field.
Not coincidentally, they both have a series of position statements that serve as subject-specific blueprints for best practices in each of their respective areas of expertise. These are my two primary sources of education and practice fundamentals for the clients and readers I serve. Additionally, there is a growing and exciting spate of research on "our tribe" of over-50 aspiring athletes that I consult regularly.
Transparency is critically important in the field of education, especially where physical health and wellness is concerned. I want you to know that we take that responsibility, and your health and fitness, very seriously.