Science

How we build the product — and why it works that way.

Deep dives on training logic, nutrition science, and the evidence behind your Wren experience. No black boxes.

Nutrition

How many calories do you need for fat loss, muscle gain, recomp, or maintenance?

How Wren uses research on energy expenditure, calorie deficits, calorie surpluses, body recomposition, and energy availability to estimate nutrition targets.

~10 min read · September 2026 Evidence

We show you what the research supports — and where the evidence ends.

Why Wren does not use cycle-phase rules during beta, the research behind its general guidance, and what the evidence does not yet support.

~8 min read · September 2026 From the Founder

How Wren stores cycle data on your device — and the tradeoffs.

When I started building Wren, I had to make a decision that scared me. I'm going to explain exactly what I decided and why — because you deserve to know.

~6 min read · April 2026 Nutrition

Why your calorie target is what it is — and how we got there

Most fitness apps hand you a number with no explanation. Here's exactly how Wren calculates your macro targets, every decision we made along the way, and where the formula ends and your body begins.

~12 min read · April 2026