Exercising fasted is beneficial for increasing vigor, mental focus, and physical strength/endurance.

“It also taught me, for instance, how to space my exercise and my food intake. It turns out for me, exercising fasted is far more beneficial. That's something I learned using Levels. And it's completely transformed, not just the spacing and timing of my diet and exercise, but also use of things like the sauna and other activities. It's been a tremendous learning for me that's really shaped an enormous number of factors in my life that have led to me feeling far more vigorous with far more mental focus and physical strength and endurance.”