Unlike glucose, ketones are considered a “clean-burning”
fuel source because they create more energy per unit of
oxygen in fewer metabolic steps, thereby generating fewer
zombie molecules (free radicals) in their conversion to
energy.^6 They also have been shown to dramatically
increase the availability of natural antioxidants like
glutathione, the body’s most potent neutralizer of free
radicals, making ketone utilization an anti-aging “two-for-
one” deal.^7
But the longevity-promoting virtues of ketones don’t end
there. Their presence in the brain has been shown to ignite
gene pathways that boost levels of BDNF, the “growth
hormone” that can facilitate healthy mood, learning, and
plasticity, further protecting our neurons from the wear and
tear of simply living.^8 As I mentioned in the previous
chapter, they also positively affect the brain’s blood supply,
increasing blood flow by as much as 39 percent.^9
BABY FAT ISN’T JUST CUTE—IT’S A BATTERY
Have you seen a baby lately? I’m talking about a newborn,
fresh out of the womb. They’re fat. And cute. But mostly
fat. Packed with stored energy prior to birth in the third
trimester, the fatness of human babies is unprecedented in
the mammal world. While the newborns of most mammal
species average 2 to 3 percent of birth weight as body fat,
humans are born with a body fat percentage of nearly 15,
surpassing the fatness of even newborn seals. Why is this