What is training fasted?

Andrew Huberman AI:

Training fasted refers to engaging in physical exercise without having consumed any calories for a certain period of time prior to the workout. This could mean exercising first thing in the morning after an overnight fast, or it could mean not eating for several hours in the afternoon before a workout. It's important to note that while fasted, some people, including myself, may still ingest non-caloric fluids like water or stimulants like caffeine. The key point is that no calories are consumed, allowing the body to rely on stored energy sources, such as glycogen or fat, during the workout. It's a highly individual preference and can depend on factors like personal comfort, workout intensity, and specific fitness goals.