Super interesting article from Nature magazine
What’s the cap on human energy expenditure? Elite athletes reveal ‘metabolic ceiling’
@Stefanie finally getting around replying to the article you shared. Interesting that a study finally proved that there is a metabolic ceiling of 2.5 x BMR. Fairly small cohort, but using double-labeled water in the study design makes it as accurate as possible, so the results are likely trustworthy!
The body is constantly working to maintain homeostasis, so it makes sense that if we spend a lot of energy in a workout or event, that we naturally decrease other daily physical activities (such as fidgeting, standing, etc.) to compensate. We might not even notice that we are doing it.
In addition, athlete’s bodies become very efficient over time, such that a 3h ride that initially had a higher cost (calorie burn), cost much less after consistent training and spending more time on the bike. This is the point folks who are trying to manage weight often miss: weight loss is accomplished mostly through nutrition, not exercise. But even then, eat too little and the body will adjust its energy expenditure related to the low food availability as well.
A very interesting and important book on the subject is BURN. In it, the author describes his research with the Hadza hunter-gatherers and how despite their extremely active lifestyle, they show similar daily energy expenditure to people in industrialised societies sitting in an office. He uses this to develop and explain the “constrained energy expenditure model”, a major concept in human bioenergetics related to the article you shared.
Along the same lines, the “calories burned” calculated in cardio machines, wearables, and training/ fitness apps are far from accurate. Using those numbers as a “budget” of how much more you can eat after a workout is a mistake, as they are typically grossly overestimated.
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One more interesting point: NEAT (non-exercise activity thermogenesis) accounts for most of our daily calorie burn. So if someone does a hard workout for 1 hour but then spends the remaining hours of he day sitting at a desk for example, they will likely be considered less active than someone who moves around a lot during the day. It can be deceiving or confusing to the person who “trains” 1h a day to find out they are not burning as much energy as they think overall.
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Heh, I forgot all about this! Thanks for your additional insights. Bodies are so weird and fascinating!
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