The Renewal

I run the experiment on myself, then send you what actually worked.

A free health newsletter by Jacob Katz. I buy every protein bar in the store, wear three trackers at once for a year, count every plant I eat, and report back with the number that made it worth doing.

About 18,000 readers. Forty-seven issues, every one of them free to read.

Why it is free

This newsletter has never earned a dollar, and that was the plan.

Health information is worth the most to the people who can least afford to buy it. Charging for it builds the wall it should be getting over. So there is no paid tier here and there never has been an ad.

That has one practical consequence for you as a reader. Nobody pays me to recommend anything, so when I tell you a popular protein bar is soy isolate and three artificial sweeteners in a nice wrapper, there is no sponsor on the other end of that sentence waiting to be kept happy.

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What lands in your inbox

I do the annoying version of the experiment so you get to skip it.

Every issue starts with something I tried or dug into properly, and ends on the number that made the trying worth it. Three that readers still write in about:

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Food

I bought every protein bar at Whole Foods

Every bar on the shelf, judged on what is in it rather than the number printed largest on the front.

The finding: when researchers tested commercial protein bars, the protein a body could actually use came out at 33 to 62 percent of the label.

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Food

I stopped counting calories and counted plants

One month tracking every distinct plant I ate. Week one was embarrassing, at eleven.

The finding: people eating 30 different plants a week carry measurably different gut bacteria than people eating ten. That bacteria weighs about two kilograms and makes roughly 95 percent of your serotonin.

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Body

I wore three health trackers at the same time

Apple Watch, Whoop and Oura, all at once, for a year. As ridiculous as it sounds and worth doing once.

The finding: which one you pick matters less than people argue about. Nike found across 1.2 million runners that the number to beat is five. Log five runs and you almost never stop.

Start here

Start with whatever is bothering you tonight.

Forty-seven issues is a lot to walk into cold. These four are where most people should begin, depending on what brought them.

You get into bed and your head will not stop. The counting trick that puts me out in a few minutes, why it works on a racing mind specifically, and the pillow question underneath it. Read: I solved sleep Mornings feel like being hit by something. What an alarm clock does to cortisol, why the first hour decides the rest of the day, and the light rule that fixes most of it for free. Read: why your mornings are difficult You want to eat better without counting anything. Swap the calorie number for a plant number. Thirty distinct plants a week, which sounds impossible until you learn that the cilantro on your tacos counts. Read: The 30-Plant Rule You know you should move more and you do not. Only two percent of people take the stairs when an escalator is right there. What choosing the harder option daily does to the rest of your decisions. Read: You're probably part of the 98%

The archive

Forty-seven issues, and the sleep ones turned into a pillow company.

Everything sent between May 2024 and February 2026, free to read with nothing in the way. Search it, or filter by what you came for.

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Who writes it

Jacob Katz, and a pillow company that started as a footnote here.

The Renewal began as a record of my own health, mostly because I was tired and wanted to know why. It kept landing on sleep. Light in the morning, the wrong bulbs at night, an alarm that dumps cortisol into you at six, and what your head rests on for a third of your life.

One issue carried a line asking readers to reply if they wanted a pillow made properly. Three hundred people did, and that became Circadian, which is now my job. The newsletter stays separate and stays free. I write it as a person who reads studies too late at night, and not as a brand.