Your own curve

The last body letter before today is the one that undoes the premise of every diet before it.

In 2015 two researchers at the Weizmann Institute in Israel, Eran Segal and Eran Elinav, put continuous glucose monitors on eight hundred people and tracked their blood sugar after every meal for a week. The finding was startling. The same food produced wildly different responses in different people. One person's blood sugar spiked after a banana and stayed flat after a cookie; another's did the reverse. The glycemic index, which ranks foods as if everyone responds alike, was wrong for a large share of people. The responses were personal, and they were predictable from the person's microbiome, body and history. In 2020 a British researcher named Tim Spector repeated it at larger scale with the PREDICT study, measuring fat and sugar responses in thousands of people, including identical twins, and found the same: even twins responded differently to the same meal.

The lesson is personalized nutrition, and I'll say the honest thing about it. Both groups have founded companies that sell personalized diet advice from these measurements, and the field is young; the evidence that eating by your own curve improves long-term health is promising but not settled. Vault Human points to the science, not the products.

What's free, and what I'd keep, is the principle. The right diet for you is the one your body measurably responds well to, and the only way to know is to look. A continuous glucose monitor, worn for two weeks, is one way. A log of how you felt ninety minutes after what you ate, which you started on day one hundred and thirty-four, is another, and it's been under your pen the whole time.

It's the right close for the table keys. A hundred and fifty-six days of letters have offered every sensible way of eating on earth. The last one says: now watch your own body, and eat by what it tells you.