Good Energy
The Surprising Connection Between Metabolism and Limitless Health
By Casey Means · Avery · 2024
A provocative 2024 book on metabolic dysfunction. Polarizing inside medicine; useful as a framework for energy management as an operator.
Editorial take
Casey Means is a Stanford-trained physician who left clinical practice to co-found Levels (the continuous glucose monitor startup) and has become one of the most amplified voices in the metabolic-health-as-root-cause space. Her book argues that most modern chronic disease (and most modern fatigue and brain fog) traces to mitochondrial / metabolic dysfunction caused by lifestyle factors that are largely reversible. The medical establishment is split on the strength of these claims, with reasonable doctors raising concerns about overgeneralization. As an operator's wellness book, however, it is unusually actionable: the chapters on glucose response, sleep, light exposure, and food quality are the most directly applicable framework I've encountered for managing the cognitive performance side of company-building. Read with the caveat that some chapters argue beyond the evidence; the lifestyle-intervention chapters are the strongest.
Last hand-checked 2026-05-18, Reasonable physicians disagree about parts of the book's stronger claims. Read the lifestyle-intervention chapters as the strongest material.
Read if you …
- are a high-output operator concerned about cognitive performance and energy management
- are interested in continuous glucose monitoring and the lifestyle-as-medicine movement
- want a metabolic-health framework you can apply tomorrow without a clinician
Skip if you …
- you want a clinically conservative medical book — this leans toward the strong-claim end of the literature
- you're allergic to wellness-industry rhetoric — parts of the book lean that direction
If you only read one chapter
The Five Tenets of Good Energy
Chapter 5's framework — sleep, light, movement, food, stress as a single integrated lever set — is the most useful 30-page operator's wellness summary in print right now.
Key ideas
- Energy is a metabolic phenomenon; cognitive 'fatigue' is often mitochondrial.
- Continuous glucose data is the highest-leverage signal an individual can act on without a clinician.
- Sleep, light, movement, food, and stress are not five problems but one integrated lever set.
- Most modern chronic disease is metabolic at root, even when classified otherwise.
About the book
Dr. Casey Means is a Stanford Medical School graduate, former otolaryngology resident, and current co-founder of Levels Health. Good Energy (2024) is her synthesis of the metabolic-health literature, framed as a personal-action manual.
The book argues that mitochondrial dysfunction underlies a majority of modern chronic disease and cognitive complaints, and lays out a five-domain intervention framework (sleep, light, movement, food, stress) for restoring metabolic function. Within mainstream medicine, the book's claims are seen by some as well-supported and by others as substantially overstated; the readable middle ground is to treat the lifestyle chapters as actionable and the medical-system critique chapters with appropriate skepticism.
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