> That's what I mean by "myth" - not that exercise burns zero calories, but that the popular mental model of "I ran for an hour so I earned X calories of food" is built on inaccurate measurements
Over the last few of decades there's been a lot of lab research calculating the gross efficiency of the human body with different factors (size, sex, fitness etc) and I think these estimates that sports apps give are very close.
If you cycle with with something that can measure power output you can calculate the mechanical work done by the body exactly during that exercise period and convert to energy "burnt" (1 watt/hour = 3.6 kJ = ~0.86 kcal). 220 Watts for an hour (I couldn't do that but a good cyclist can) is about 800 calories.
To the degree the body diverts any housekeeping or thermogenic calories to exercise calories, which from basic biological adaptivity and thermogenic control must be true at some level, that math will be misleading.
Not that doing x work doesn’t burn y energy, but that +x work in exercise does not burn +y energy at the end of the day.
Exercise is an alternate heat source, approximately 1-to-1 with thermogenic heat (albeit, not distributed as evenly). So much so that our body has to switch to cooling strategies.
And the body can respond to exercise expenditures by reducing other expenditures and using calories more parsimoniously in other dimensions.
It is interesting that during periods in which I have a habit of daily low intensity exercise, I feel like I have more energy than periods I don’t do any exercise, even if my calorie intake is the same.
Another noticeable effect is any allergies from local plant life I get clear up quickly during and after exercise. My immune system runs a tighter, less reactive ship.
Those baseline calories are not just often underestimated in a static sense, but are also dynamically adaptable.
One reason may be is that we evolved to burn far more overt calories through a day than our extra-exercise day burns. Our body has mechanisms for storing surpluses but almost certainly raises baseline use as well. Which is easily diverted back to exercise.
On the other hand, beyond any net expenditure from regular lifting weights (as work), to the degree greater muscle mass is achieved and maintained, weight lifting directly raises the body’s baseline expenditures.
Over the last few of decades there's been a lot of lab research calculating the gross efficiency of the human body with different factors (size, sex, fitness etc) and I think these estimates that sports apps give are very close.
If you cycle with with something that can measure power output you can calculate the mechanical work done by the body exactly during that exercise period and convert to energy "burnt" (1 watt/hour = 3.6 kJ = ~0.86 kcal). 220 Watts for an hour (I couldn't do that but a good cyclist can) is about 800 calories.