Learn
Understand your health data
Plain-English explainers for the numbers your devices track, written by the coaches who read them.
Getting started
Heart and cardio
Guide
What Is HRV?Heart rate variability explained, what a good number is, and how to raise it.
Guide
VO2 Max ExplainedWhat a good score is by age and how to improve it.
Guide
Zone 2 Heart RateHow to find and train your real aerobic base pace.
Guide
Active Zone MinutesHow many you need per day and why minutes in zone beat steps.
Guide
Resting Heart RateWhat a good resting heart rate is by age and fitness, and what moves it.
Guide
Max Heart RateHow to calculate it and why 220 minus age is only a rough estimate.
Guide
Heart Rate RecoveryHow fast your heart rate drops after exercise, and what it says about fitness.
Strength and training
Sleep and recovery
Guide
Sleep DebtWhat it is, how it builds, and how to recover it.
Guide
Menstrual Cycle PhasesThe four phases and how to read training, recovery, and nutrition by phase. Calendar-based, not medical.
Guide
Sleep StagesDeep, REM, and light explained, and how much deep and REM you actually need.
Guide
Readiness ScoreWhat a readiness or recovery score is, and how Oura and Whoop compute it.
Nutrition and body
Guide
TDEE CalculatorEstimate your daily energy burn, plus how we compute your real one.
Guide
Macros for RecompositionProtein and calories to lose fat and build muscle at once.
Guide
Protein IntakeHow much protein per day by bodyweight and goal.
Guide
Calorie DeficitWhat a calorie deficit is and a safe rate to lose fat.
Guide
Body Fat PercentageWhat a healthy body fat percentage is by age and sex.
Calories and energy
Explainer
What Is TDEEWhat total daily energy expenditure is made of, and why yours keeps moving.
Explainer
Maintenance CaloriesThree ways to estimate the intake that matches what you burn.
Explainer
Calories Burned AccuracyWhat a watch can and cannot tell you about your calorie burn.
Explainer
Calories In, Calories OutThe energy balance equation, and why the scale ignores it daily.
Read your own numbers, every day.
Connect Apple Health, Fitbit, or Oura and let one coach turn your metrics into plain-English guidance. Free Basic, with Founder Pro at $4.99/month through October 15.
