mymir vs MacroFactor: The Missing "Did It Work" Data Point

MacroFactor earned its reputation the hard way: built by Greg Nuckols and Eric Trexler of Stronger By Science (with backing from fitness educator Jeff Nippard), its adaptive algorithm recalculates your calorie and macro targets weekly based on your actual weight-trend and intake data, not a static formula. After 6–8 weeks of consistent logging, that estimate gets remarkably accurate. For people who lift, cut, or bulk with any seriousness, that precision is genuinely valuable, and mymir does not try to out-algorithm it on pure macro-target accuracy.

What MacroFactor is not built to do is look past macros. It will tell you, precisely, how many grams of protein to eat today. It will not tell you whether cutting your late dinners, fixing your fibre gap, or changing your sleep timing is the thing actually moving the needle — because those questions sit outside what it measures.

Precision vs. explanation

MacroFactor answers "what should my numbers be, adjusted for reality?" extremely well. mymir answers a different question: "out of everything going on, what is the one thing worth testing next, and did it work?" The two are not competing on the same axis — a serious lifter might reasonably want both.

What mymir adds on top

• Structured experiments — any change (not just calories or macros) gets run as a five-day test with a measured before/after, instead of being left to a weight-trend graph to explain.
• Pattern detection — mymir surfaces behavioural patterns like weekend drift or low-fibre stretches on its own, rather than waiting for you to notice them in a log.
• Coach check-ins — a light, non-shaming nudge when your logging goes quiet, not just a silent gap in the data.
• Apple Health context — sleep and activity are read alongside food, so a stall gets checked against more than macros alone.

Who each app is really for

If your goal is dialled-in body recomposition and you already know exactly what levers you are pulling, MacroFactor's adaptive targets are hard to beat. If you want an app that also tells you which lever to pull next and proves whether pulling it worked, that is the gap mymir is built to close.

Frequently asked