Edward F. Adolph Distinguished Lecture. Protein and energy metabolism: a state of flux.

Physiology processes are integrated, dynamic, and periodic and thus benefit from methods that capture their dynamic nature. Since we are often limited to discrete sampling points in physiological studies, many methods provide snapshots of a system. However, these snapshots can at times be limited in their ability to understand the underlying events. This article is a summary of my 2025 Adolph Lecture and discusses how tracers (particularly, stable isotopes) go beyond mere snapshots to provide important insight into dynamic events. The article is part review and part narrative that provides insight into my scientific journey and the thought process that went into the design of the highlighted studies. I primarily feature articles published in APS journals and note what insight the tracer-based measurements provide. I hope that the reader comes away with an appreciation of the complexity of physiological studies and why tracer-based studies are, in fact, mechanistic.