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Why Your Workout Might Not Add Calories Back

Metabolism1 min readAinsworth et al., Compendium of Physical Activities

A MET is a multiple of resting metabolism, so 1 MET is simply lying still. That means the raw MET calculation for an activity already contains the calories you'd have burned doing nothing for the same length of time. Your calorie target already contains those resting calories too, via your activity multiplier. Add the raw figure to the target and the resting portion gets counted twice, which is one reason exercise trackers have a reputation for overfeeding people. Kriterion reports the energy spent *above* rest, matching what Apple Health and Health Connect call active energy.

There's a second layer to this: your activity level already assumes a certain amount of daily movement, so an ordinary day is priced in before you log anything. Only genuinely unusual days add to your budget. And once the Adaptive Target has enough of your data, nothing is added back by default, because your expenditure is then measured from what your weight actually did rather than estimated from a table — though that measurement describes your *average* day, which is why Premium can opt into crediting the amount an unusual day goes past it.

How Kriterion uses this

It is why Kriterion credits a session the way it does, instead of handing back the whole figure a watch reports and quietly counting some of it twice.

References

  1. Ainsworth BE, Haskell WL, Herrmann SD, et al. 2011 Compendium of Physical Activities: a second update of codes and MET values. Medicine & Science in Sports & Exercise, 2011.
  2. Jetté M, Sidney K, Blümchen G. Metabolic equivalents (METS) in exercise testing, exercise prescription, and evaluation of functional capacity. Clinical Cardiology, 1990.

Kriterion is the app this reasoning is built into

It measures your maintenance calories from what you actually ate against what the scale actually did, tells you how firmly the number is pinned down, and checks its own past predictions against your results. Free logging, UK food data, and no ads.