(AMD), suggesting that AMD may in fact be a form of
diabetes of the eye! In light of insulin’s role in suppressing
fatty acid release, reducing carbohydrate intake (and thus
insulin secretion) could provide a meaningful and safe
lifestyle modification for a substantial at-risk population.^5
(AMD remains the leading cause of visual impairment in
Westerners over the age of fifty.)
Even the brain can use fat for fuel once fat is broken
down into chemicals called ketone bodies. Ketone bodies, or
simply ketones, become elevated with periods of fasting,
very-low-carbohydrate diets, and by consuming certain
ketone-producing foods. They are also produced during
vigorous exercise, once glucose stores have become
exhausted. But ketones aren’t just a fuel—they also act as a
signaling molecule, flipping switches in the brain that seem
to have a range of beneficial effects. Among them is the
ability to boost BDNF, the brain’s ultimate neuroprotective
protein. However, chronically elevated insulin keeps us
metabolically inflexible by blocking ketones from being
generated. “The inhibition of lipid (fat) metabolism by high-
carbohydrate diets may be the most detrimental aspect of
modern diets,” opined Sam Henderson, a well-known
researcher in the area of ketones and Alzheimer’s disease.
(You’ll learn more about ketones and all of their therapeutic
and performance-boosting potential in chapter 6.)
The key to allowing these fatty acids to come out and
play is reducing insulin, plain and simple. Italian researcher
Cherubino Di Lorenzo (who actually studies the effects of
ketones on migraine headaches) perhaps said it best: “You
could think of this [fat-mobilizing] process as the body’s