Your smartwatch is lying to you about how many calories you burned in your last workout
news.fiu.edu
A study found that fitness trackers overestimate calories burned, and accuracy worsens as body fat increases.
  • Earthwormjim91@lemmy.worldEnglish
    2·
    21 days ago

    because apparently we humans are all differently efficient in converting calories into watts.

    We’re not that different though. It doesn’t vary that much between people. It’s pretty universally 20-25% of energy gets converted into mechanical energy, with the other 75-80% lost as heat.

    What does differ is how mechanically efficient the bike is. A commercial gym stationary bike might only be 80% efficient at converting the energy put into the pedal down into the flywheel, and that is what gets read by the power meter. A high end race bike is above 95%.

    Due to the roughly 25% efficiency, the math of kilojoules to calories burned is almost exactly 1:1.

    Outside of a clinical lab where you get hooked up to a machine that reads the actual CO2 from your breath as you exercise, a power meter is the most accurate you’re going to get though.