Casey Means, MD, a Stanford-trained physician, cofounder of Levels, and author of the new book Good Energy, joins Vijay Pande,  PhD, founding partner of a16z Bio + Health.Together, they discuss the downsides of physician specialization, the rising tide of chronic illness in the U.S., and how tracking biomarkers might allow people to determine the best nutrition options for their unique physiology. Casey's book is available here.