Opening Up the Ketone Firehose
Nearly every major religion has their version of a fasting
protocol, from the Islamic month of Ramadan to the Jewish
Day of Atonement, Yom Kippur. In the Book of Acts, from
the Christian New Testament, it is said that believers would
fast before making important decisions. What all of these
ancient traditions have in common is that they recognized
the psychological and physiological effects of fasting long
before they understood the science behind it.
After a person has finished digesting the last calorie from
a meal, the first source of backup fuel that the brain will tap
is from the liver. The liver plays hundreds of incredibly
important roles in the body—you can consider it a
multipurpose high-tech manufacturing plant, capable of
packing, shipping, storing, and disposing an infinite array of
important chemicals and fuels. In the previous chapter, you
learned about the liver’s job of recycling cholesterol carriers
like LDL, but another important role is its ability to provide
a small buffer of stored sugar called glycogen.
When blood glucose levels begin to drop, the liver
releases glycose into the blood. The liver’s storage capacity
is fairly limited, holding only about 100 grams of glycogen.
That means this backup source of sugar is short-lived,
lasting only about twelve hours, give or take, depending on
activity levels.
After the liver runs out of stored sugar, your brain
becomes the man-eating Audrey II from Little Shop of
Horrors, demanding to be fed. This is what most people feel
when they experience the combination of being hungry and