The six subject groups

The twenty chapters fall into six groups. They are arranged so that a reader moving through the volume in order builds from mechanism to application, but each chapter is written to be read alone, and the groups below are a map rather than a required route.

Foundations Chapter 1

The first chapter covers how the body works and how health claims are tested. It is the chapter most readers skip and the one that returns most, because every claim in the nineteen that follows is assessed with equipment supplied here. Its four sections move from structure to scrutiny: how the body is built and why several of its arrangements are compromises rather than solutions; how it operates, with particular attention to the regulatory systems that keep variables steady and therefore resist being moved; how health research is produced, what different study designs can and cannot establish, and where the published record is distorted by what does not get published; and finally what any of it means for one person, including why a normal reference range is a statistical construction rather than a boundary between health and disease. A reader who takes only the third section has still gained the most transferable thing in the volume.

Food Chapters 2 through 8

Seven chapters cover eating, and they are ordered so that a reader builds from food to mechanism rather than the reverse. Chapter Two begins with whole foods and ordinary meals, which is where most readers actually live. Chapter Three covers the science underneath: macronutrients, micronutrients and metabolism. Chapter Four covers the gut and its microbiome, a field where genuine discovery and commercial overreach arrive together. Chapter Five sets the major diets against one another. Chapter Six covers fasting and meal timing. Chapter Seven covers weight loss and, more importantly, its maintenance, which is the part that fails. Chapter Eight covers metabolic health, blood sugar and the chronic diseases connected to them, and contains some of the most consequential findings in the volume, including the demonstration that type 2 diabetes can be put into remission. This is where the published literature disagrees with itself most sharply, and the chapters are written to show disagreement rather than to resolve it. Readers working through them will find the camps agree on considerably more than their public arguments suggest.

Movement Chapters 9 through 11

Three chapters cover training. Chapter Nine establishes why exercise matters and how to begin, and it rests on the strongest evidence in the collection: physical activity has better outcome data behind it than any supplement, diet or intervention described anywhere in these twenty chapters, and the largest gains accrue to the least active rather than to the already fit. Chapter Ten covers resistance training, which is the single intervention with the greatest effect on how a body ages, and which is systematically underdone by the people who would benefit most. Chapter Eleven covers cardiovascular training, running and endurance, including the two measures, VO2 max and zone 2, that have moved from laboratory shorthand into general conversation and been distorted in transit. A reader new to exercise should treat Chapter Nine as the entry point to all three rather than starting with whichever activity appeals.

The body under load Chapters 12 through 14

Three chapters cover what happens to a body that is being used. Chapter Twelve covers mobility, flexibility and functional movement, where the gap between confident popular claim and supporting evidence is the widest in the collection: stretching before activity does not prevent injury, movement screens do not predict it, and posture correlates with pain far more loosely than the industry built on it assumes. Chapter Thirteen covers injury, pain and rehabilitation, organized around the finding that pain and tissue damage are related but distinct, which changes how a scan result should be received, and which explains why several standard treatments have failed in trials. Chapter Fourteen covers recovery, rest and sleep, where sleep turns out to be the most powerful recovery intervention available, the one with by far the best evidence, and the only one nobody can package and sell.

Mind and time Chapters 15 and 16

Two chapters cover the nervous system and time. Chapter Fifteen addresses breathing, stress physiology and the mind-body relationship, and it holds both the best-established and the least-established material in the volume, sometimes on facing pages: that chronic stress alters immune and cardiovascular function is well demonstrated, that personality causes cancer is not, and the distance between those two claims is where most of the harm in this literature is done. Chapter Sixteen covers longevity and health span, a field with the widest gap in the collection between what has been shown in laboratory organisms and what has been shown in people. No compound discussed in it has been demonstrated to extend human lifespan. The useful distinction throughout is between living longer and living well, and the second is the more achievable target.

Person and practice Chapters 17 through 20

Four chapters close the volume. Chapters Seventeen and Eighteen cover women's health and men's health, meaning what genuinely differs by sex, which is substantial in some areas and much smaller than marketing suggests in others. Both are shaped by the same history: women were excluded from most clinical research until the 1990s, and men consult clinicians less and present later. Chapter Nineteen covers habits and behavior change, which determines whether anything else in the volume matters, and which is the field most disrupted by psychology's replication crisis. Chapter Twenty treats the person whole rather than by system, gathers the works that shaped this field, including several that were influential and are now substantially wrong, and closes the collection with what survives when the twenty subjects are set beside one another.

Several chapters pair closely and are better read together than apart. Chapter Nine underlies Ten and Eleven, and a reader new to exercise should start there rather than with either. Twelve and Thirteen overlap wherever movement and pain meet, and a reader with existing pain should begin with Thirteen. Fourteen and Fifteen both concern the systems that recover a body rather than load it. Chapter Nineteen relates to all of the others, because a reader who cannot act on what they have learned has gained nothing from learning it.

How the twenty chapters are constructed, and what the tiers and starred recommendations mean, is described next.

Source: the printed volume, pages 11–12. Reproduced from the printed volume.