Many cancer cells rely heavily on glucose (the Warburg effect) and cannot efficiently use ketones. A strict ketogenic diet may starve these tumors while nourishing healthy cells. In one case, it led to a 70% reduction in cancer markers in six weeks, far exceeding chemotherapy's expected 30%.

Ferriss notes significant physiological changes while in ketosis, including needing 2-3 fewer hours of sleep and at least doubling his breath-hold time. He also experiences a dramatic reduction in ruminative thoughts, improving mental clarity and sleep onset.

While short-term keto adaptation (first month) may show no power gains, long-term adaptation (6-18 months) trains muscles to efficiently use fat as fuel. This results in significant power increases, with studies on soldiers showing up to a 50% improvement over their non-keto counterparts.

The goal of fiber is to feed gut bacteria that produce butyrate, a key acid for gut health. However, you can bypass this. Being in a ketogenic state directly provides beta-hydroxybutyrate (a ketone) to the gut, strengthening the microbiome without requiring high fiber intake.

Beyond being an alternative fuel source, the ketone body beta-hydroxybutyrate (BHB) functions as a signaling molecule. It acts as an HDAC inhibitor, which can activate genes that enhance the body's antioxidant and cellular defense mechanisms, a pathway of interest in cancer therapy.

Long-term, consistent use of ketone esters based on 1,3-butanediol, a very common formulation, may lead to liver toxicity. This risk exists even at doses that are not considered excessively high, such as those used by endurance athletes or in protocols for Alzheimer's.

The anxiolytic effect of ketosis has a clear neurochemical basis. Elevated ketones increase the levels of the enzyme GAD (glutamic acid decarboxylase), which converts the brain's primary excitatory neurotransmitter, glutamate, into its primary inhibitory (calming) neurotransmitter, GABA, creating a more stable neurological state.

A moderate level of blood ketones, around 1.2 to 2 millimolars, can have an anxiolytic (anxiety-reducing) effect. However, spiking ketone levels significantly higher, often through large doses of exogenous supplements, can paradoxically increase anxiety and lead to a subsequent crash.

Ketones are a more efficient energy source than glucose, producing less metabolic “trash” (oxidative stress). Crucially, they can penetrate the blood-brain barrier and fuel brain cells even when they've become resistant to insulin, directly combating cognitive decline and brain fog.