←back to thread

181 points andrewstetsenko | 2 comments | | HN request time: 0.538s | source
Show context
mojosam ◴[] No.41896353[source]
it sounds like the authors are suggesting that additional energy usage caused by stress can, in isolation from other causes, be a mechanism for disease. But that doesn’t make much sense:

  - our metabolisms are adaptable, so why wouldn’t this increase in energy use simply be offset by an increase in energy production? It can’t be that people who are stressed in general aren’t getting enough energy, because that would correlate stress with weight loss, but I would argue that there are plenty of overweight people with stress.

  - if the argument is that an increased metabolism by itself is the culprit, then why wouldn’t people with higher metabolisms in general — like anyone who exercises regularly, but certainly athletes — not also experience more disease? If your answer is “that’s different for some reason”, then that means that increased energy usage and metabolism is not by itself the cause, which suggests it may not be the cause at all.
Furthermore, even granting the supposition that stress requires increased energy usage, their abstract doesn’t make much sense:

  - “Living organisms have a limited capacity to consume energy.” Okay, so that means that no matter how stressed we get, there’s a cap to the energy we can use. But how is that relevant, since it also applies to exercise or other energy utilization by the body? Why does a limited capacity to consume energy only apply to stress?

  - “Overconsumption of energy by [stress handling] brain-body processes leads to … excess energy expenditure above the organism’s optimum”. Thats basically a tautology, but more importantly, it doesn’t tell us that energy consumption above “optimal” — which seems extremely vague — is a bad thing.

  - “In turn, [excess energy consumption above the optimal] accelerates physiological decline in cells, laboratory animals, and humans, and may drive biological aging”. So that “may” is a pretty good reason to dismiss this, since again why wouldn’t this lead to increased disease among athletes or anyone with higher metabolism?

  - “Mechanistically, the energetic restriction of growth, maintenance and repair processes leads to the progressive wear-and-tear of molecular and organ systems” Maybe, but why are they energetically restricted if metabolism has increased to provide more energy? And again, why don’t we then see increased disease and aging in anyone who exercises regularly, since that exercise not only uses energy that restricts growth, maintenance and repair, but exercise causes more need for repair.
I think the core problem is that it’s all going to boil down to how you define “optimum”, which the authors conveniently don’t. The authors are going to be left with defining “optimum” as meaning “that energy usage which does not cause disease”. But that’s no different than simply claiming “stress causes disease”, so this model describes nothing, since it tells us nothing about how to identify non-optimum energy usage or how non-optimum energy usage causes disease.
replies(2): >>41896958 #>>41897712 #
anon84873628 ◴[] No.41897712[source]
>Okay, so that means that no matter how stressed we get, there’s a cap to the energy we can use. But how is that relevant, since it also applies to exercise or other energy utilization by the body? Why does a limited capacity to consume energy only apply to stress?

It doesn't. That limited capacity to consume energy applies to exercise, brain activity, thermogenesis, digestion, and every other biological process as well. It is a fundamental aspect of cellular biology and a major focus in the field of exercise physiology.

Fitness training is the very slow and deliberate process of pushing these limits tiny percentages higher.

I suggest you build some practical and theoretical knowledge of the field before dismissing the paper.

replies(1): >>41904229 #
1. authorfly ◴[] No.41904229[source]
I absolutely don't doubt you but can you provide some accessible education resources or some sports science/biochemistry papers for the claim around "That limited capacity to consume energy applies to exercise, brain activity, thermogenesis, digestion, and every other biological process as well. It is a fundamental aspect of cellular biology and a major focus in the field of exercise physiology." ?

What energy are we talking about here exactly? ATP?

replies(1): >>41905902 #
2. anon84873628 ◴[] No.41905902[source]
Yes. Metabolism is rate limited by countless chemical reactions. Energy sources need to be broken down and moved around the body. Waste products need to be removed. Mitochondria only work at a certain rate. You can increase the number of mitochondria but that hits a practical ceiling as well.

You can start with the Wikipedia article for Metabolism or search for "metabolic scope" and "metabolic efficiency".