anywhere from 30 to 150 grams per day. We will talk more
about carb amounts and timing in chapter 11.
Ketones: A Life Raft for the Aging Brain?
Now that you know how to enter a state of ketosis, you
should be aware that the benefits of allowing the brain to
“burn” ketones instead of glucose don’t end at the fact that
they are a cleaner-burning fuel source. One of the major
benefits of supplying ketones to the brain that I have yet to
mention is that certain brains may actually work better when
given the chance to run on ketones. These brains may be
unable to process glucose effectively, but are given little to
no alternative thanks to our “keto-deficient” diets, a term
coined by ketone researcher Sam Henderson.^26
A prime example may be carriers of the most well-
defined Alzheimer’s risk gene, the ApoE4 allele. Carriers of
either one or two copies of this gene, which make up more
than a quarter of the population, have been demonstrated to
exhibit low glucose metabolism in the brain.^27 This occurs
seemingly across the age spectrum, starting as early as the
twenties and thirties, which is well before the age at which
memory-related symptoms typically emerge.
Carriers of the ApoE4 allele have either a two- or
twelvefold increased risk of developing the disease
depending on whether they’ve inherited one or two copies.
Despite the increased risk, however, many ApoE4 carriers