Book excerpt: Neurosurgeon and wildly controversial Paleo blogger Dr. Jack Kruse gives us his first book, Epi-paleo Rx: The Prescription for Disease Reversal and Optimal Health. Kruse, who used his findings to lose 140 pounds and pack on muscle, takes the reader through his prescriptions for obesity, diabetes, heart disease, osteoporosis, autoimmunity, brain health, and aging. The material weaves together surprises from our Ice Age origins with the new science of epigenetics, or the effect of diet and environment on gene expression. A champion of “biohacking,” the art of tinkering with one’s own biology, Kruse pounces on his own profession’s ineptness when it comes to chronic conditions and urges readers to take health care into their own hands. He discusses which labs to order and why, why your doctor is obligated to write you a prescription you don’t need, the vital roles daylight and darkness play in metabolism, and the optimal diet for different stages of health and different times of year. Perhaps Kruse’s more fascinating contributions to Paleo literature are his findings on cold therapy—the effect of cold environments, immersion in cold water, and ice pack therapy on disease reversal, pain, and optimal living. Kruse explains how our origins as cold-adapted mammals hold the key to disease reversal, using a shocking biohack to prove his theory. The Epi-paleo Rx is the result of Kruse’s abundant research and clinical application in his practice as a neurosurgeon. Kruse questions conventional wisdom about human metabolism and chronic disease, arguing science has incomplete information when it comes to insulin resistance, diabetes, obesity, and their related illnesses. By examining the human body through the prism of our early beginnings and the science of epigenetics, we find each of us already possesses the “owner’s manual” to reverse disease and live optimally.