Four numbers

In 1948 the U.S. Public Health Service enrolled a little over five thousand people in a mill town outside Boston and started measuring them every two years to find out why Americans were dying of heart attacks. They are still measuring the grandchildren. The Framingham Heart Study invented the phrase "risk factor" in 1961, and almost everything your doctor checks at a physical came from it.

Vault Human takes four numbers from that tradition that you can read at home. Steps, which you wrote on day one. Sleep, which the log is catching. Waist, which a tape measures. The cuff, your blood pressure, which a twenty-dollar machine or a pharmacy kiosk reads for free.

Why these four. Steps are the cheapest measure of how much you move, and movement predicts more than most lab values. Sleep is the number people lie to themselves about most, and the log fixes that by asking every night. Waist beats weight because it measures where the fat is, and the fat around the organs is the fat that matters; the lines most doctors use are about forty inches for men and thirty-five for women, and the cleaner rule is waist under half your height. The cuff is the risk factor that study found first, and it is still the one that kills the most people who never felt a thing. Most adults over forty are above the textbook reading and don't know.

This key does not tell you what to do about any of the four. The practices for that come in later months. This key asks you to look. You cannot know yourself while refusing to know what your body is doing when you aren't watching.

My first set were not what I expected either. I wrote them down anyway. That was the point.