there may be room to “top off” the brain’s supply to the
benefit of one’s cognitive function. But low meat eaters
aren’t the only group who may benefit: the body’s ability to
produce creatine and supply it to the brain may diminish
with age.^17 One surprising study in elderly omnivores found
that creatine supplementation did boost cognition.^18 And,
finally, carriers of the Alzheimer’s risk gene, the ApoE4
allele, have lower levels of brain creatine.^19 They, and those
who are at risk or are already experiencing cognitive
symptoms, may benefit from the neuroprotective and
energy-sustaining aspects of creatine. (Be sure to double-
check with your physician before taking creatine
supplements, especially if you have kidney problems.)
The Ketogenic Diet
The classical ketogenic diet is the gold-standard means
of dramatically increasing ketone production without having
to engage in time-restricted feeding or dropping calories.
The diet focuses on minimizing insulin secretion with an
extremely restricted carbohydrate intake, deriving 60 to 80
percent of calories from fat, 15 to 35 percent from protein,
and 5 percent from carbohydrate.^20 For someone on a
ketogenic diet, concentrated sources of carbohydrates,
whether from sweet fruit, grains, or starchy vegetables like
potatoes, are prohibited.