Human basal metabolic rate has declined over the past 30 years | Hacker News Reader

Human basal metabolic rate has declined over the past 30 years

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This is very surprising!

Some outtakes from the study:

* Total Energy Expenditure reduced by 7.7% in males, 5.6% in females.

* Basal Energy Expenditure reduced by 14.7% in males (!!), 2% in females**

* They adjusted for body composition by looking at fat-free mass, fat mass, and age as predictors.

* To check these observations a systematic review of literature on BMR from the US and Europe over the past 100 years has shown a decline of BMR by about 0.34 MJ. Consistent, but lower numbers than this study.

The study also outlines some potential contributors to the reduction of BEE such as diet, decreased immune function, but also methodological artefacts.

>In the early years, measurements of BMR were made by using mouthpieces to collect respiratory gases, and recently such devices have been shown to elevate BMR by about 6%. A second possibility is that early measurements paid less attention to controlling ambient temperature to ensure that individuals were at thermoneutral temperatures.

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I've personally suspected something like this about myself. Whenever I've tracked my calories, it seemed that my actual metabolic rate was a bit lower than the various calculators suggested. I chalked it up to poor calorie tracking and wrong activity level assumptions though.

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** not statistically significant, inclusion of one study caused the reduction to be only 2%, but there was no reason to discount the study

Seriously, how did you get to the study from that lone Twitter post? I see nothing to click on when I load the link.

I didn't click on the link, but I googled the title and found a Nature article: https://www.nature.com/articles/s42255-023-00790-2.epdf

Ah, the obvious. I thought I'm missing something because I don't know how to use Twitter.

You have to be logged in. Then you can scroll up to see the rest of the chain of posts. The first post has the link to the study.

Ah well, i've never had a twitter account and I'm not going to start now.

I used nitter which shows the whole thread https://nitter.net/JohnSpeakman4/status/1651246450314211329

This post should have started with a link to the Nature article, instead of yet another useless link to the dead bird site.

Why is this a link to what used to be Twitter? It’s very unhelpful.

I tried looking at the poster’s other posts for more info than a single tweet, but now Xes are no longer displayed chronologically so all I got were posts from 2019. When I managed to find a link it said it was expired.

Please don’t post Twitter links. Even prior to the changes this looks like it would have been one of those annoying essays divided into 2 tweets.

Ah, I've hit that out of order "feature" too.

I noticed the timeline order is fixed whenever I log in.

sorry!, i messed up the link -- i tried to link to the first tweet, which is viewable not logged in, and has a link to the study; then if you are logged in, it has a very helpful more informal discussion of the results.

but i accidentally linked to the middle of the thread, which was not useful.

I'm not sure how to really interpret this. Human body temperature has also declined.

https://www.nytimes.com/2020/01/09/well/live/body-temperatur...

Activity levels?

Aka we've turned into coach potatoes, sit in cars / offices all day? As opposed to walking, manual labour, cycling & so on.

The study did look at activity levels separately. It found that activity levels have actually gone up, but I'm unsure what they specifically mean under "activity levels" ie would driving instead of walking county?

Sedentary lifestyles, passive rather than active entertainment (TV shows rather than engaging in sports)?

I was also thinking computers offloading our very energy demanding brains but stress diseases and exhaustion is in fact up so I think work compensates more than enough there.

But that’s also interesting because the energy dip has to offset our cognitive overload from our higher paced society and demands as well. And with the brain being among the most taxing things we have, that sounds big. Buuut I have a feeling our low activity lifestyles are just that influential.

Body temperature would be a big factor. As far as I can tell thermoregulation is the highest consumer of energy in the human body.

I don't think there is anything surprising here. I pretty much expected it.

We (humanity) are trying to find ways to feel more comfortable and these inevitably tend to mean a) optimising our environment to require less exertion and b) eating more carbohydrates.

Both lower BMR.

Impact on (-and of) unchanged diet expectations?

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