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Something I've been wondering: > [When you loose weight], your body looks for ways to conserve energy. Your muscles work more efficiently, for example, Ard say

Something I've been wondering: > [When you loose weight], your body looks for ways to conserve energy. Your muscles work more efficiently, for example, Ard says, so walking that normally burned 100 calories might now burn only 90. By making you want to eat more and burning fewer calories, your body is eventually able to slow weight loss down to zero. How exactly is your body able to accomplish the same task with less energy? What are you giving up? Do you become tired more easily, or wear out your muscles more quickly? Or does loosing weight just turn you into a more efficient super-human (albeit perhaps not in a way you would like)? Would it be desirable for, say, an ultra-marathon runner (who I assume needs to consume as little energy as possible) to spend a year gaining and then loosing a bunch of weight, to make their body more efficient?

plasticchris 3y ago
There's the obvious - you are now lighter and so less work is being done to move your body.
throwup238 3y ago
> How exactly is your body able to accomplish the same task with less energy? Mitochondrial uncoupling proteins [1]. They control how much energy gets converted to ATP in the mitochondria and how much is lost as waste heat. As you enter a caloric deficit, UCP1 is downregulated and the mitochondria adapt to lose less energy to heat. [1] https://en.wikipedia.org/wiki/Uncoupling_protein https://en.wikipedia.org/wiki/Uncoupling_protein
- RobotToaster 3y ago
  It's a real shame that uncouplers like DNP have such bad side effects, from a theoretical standpoint they are perfect.
- paulmd 3y ago
  the funny thing is people (including on HN) have spent years arguing that the human body is a blast calorimeter and that everyone absorbs the same amount of energy from the same amount of food and therefore CICO is the only thing that matters or can help. and oh look here's the protein which controls how much you absorb from it. CICO is the only actionable advice for an individual (at least in the absence of such drugs) but there are still major questions about things like endocrine disruptors etc. The rise of obesity is far too broad-spectrum (even in feral cat colonies or lab rat populations that shouldn't be affected) to really be attributable to just "people have desk jobs". Lots of people have desk jobs all over the world and obesity is not evenly distributed, and the story has always been that "exercise doesn't matter, what you eat controls your weight" so things like biking vs driving should have a relatively small effect. But people wanted to turn it into a moral hazard, and they did. Fat people have always been a socially-acceptable target to punch down on. "I'm actually helping them, you see".
  - hollerith 3y ago
    You misunderstand the details, but your overall point is correct, IMO.
  - elevatedastalt 3y ago
    CICO looks like dumb advice ONLY if you think it to mean that you should be literally summing the nutritional labels of the foods you consume and whatever calorie estimates your smartwatch shows you and treat it as gospel. Both the CI and CO numbers can have very large error margins, however, the fact that their difference, if leading to a caloric deficit, will cause weight-loss is irrefutable truth. If you do a diet for 14 days and have no change in weight, it just means you need to reduce consumption more. CICO isn't unfair because it's incorrect. It's unfair because for some people following CICO comes trivially, while for others it's literally the hardest thing they will ever do in their lives. And that's why I do sympathize with people who find it hard to lose weight. You are fighting against your most primal instincts (the desire to eat). But that doesn't mean CICO is incorrect.
    - xk_id 3y ago
      oh thank god someone else put in the effort to type this, so I didn't have to. yes, this view is 100% correct.
  - thefz 3y ago
    CICO is thermodynamics. People argue against it because it means that to lose weight, you either burn more or, drum roll, get in less. There is really no way out of physics, argue all you want.
  - xboxnolifes 3y ago
    Dynamic bounds doesn't mean no boundary. Maybe we viewed different communities, but I rarely came across people who thought calorie counting was 100% accurate. Human bodies are complex systems. But, calories in is still an upper bound, and calories out is still roughly accurate when tracking exercise. The big contention is the middle part.
- Wowfunhappy 3y ago
  But what is the downside? (I mean, other than weight gain.) You just get more energy for free? Why doesn't the body use less energy by default?
  - xk_id 3y ago
    The physiological adaptations to caloric restriction in general are extremely broad and not all are related to the tradeoff in thermogenesis. But to answer your question, you basically get cold much more easily, basically all the time. As for why the body isn't always operating as efficiently as it does on CR: it's possible that the "default" state we are in today, due to caloric overabundance, is actually a hyper-active state, characterised by excessive protein synthesis, tissue hypertrophy and libido, among other things. These are all very costly in terms of metabolic resources. When fewer calories are available, developmental processes slow down, metabolism switches to catabolic autophagy (which has the benefit of recycling old and damaged organelles) and reproductive function is deprioritised, in favour of optimising survival. The evolutionary basis is to ensure survival, until comfortable sustenance is found again, so that reproductive concerns can be resumed.
xyzelement 3y ago
// How exactly is your body able to accomplish the same task with less energy? Maybe a useful analogy is that my hybrid SUV and a v8 Range Rover sport consume very different amount of gas even for driving the same distance at the same speed.

plasticchris 3y ago

There's the obvious - you are now lighter and so less work is being done to move your body.

throwup238 3y ago

> How exactly is your body able to accomplish the same task with less energy? Mitochondrial uncoupling proteins [1]. They control how much energy gets converted to ATP in the mitochondria and how much is lost as waste heat. As you enter a caloric deficit, UCP1 is downregulated and the mitochondria adapt to lose less energy to heat. [1] https://en.wikipedia.org/wiki/Uncoupling_protein https://en.wikipedia.org/wiki/Uncoupling_protein

RobotToaster 3y ago
It's a real shame that uncouplers like DNP have such bad side effects, from a theoretical standpoint they are perfect.
paulmd 3y ago
the funny thing is people (including on HN) have spent years arguing that the human body is a blast calorimeter and that everyone absorbs the same amount of energy from the same amount of food and therefore CICO is the only thing that matters or can help. and oh look here's the protein which controls how much you absorb from it. CICO is the only actionable advice for an individual (at least in the absence of such drugs) but there are still major questions about things like endocrine disruptors etc. The rise of obesity is far too broad-spectrum (even in feral cat colonies or lab rat populations that shouldn't be affected) to really be attributable to just "people have desk jobs". Lots of people have desk jobs all over the world and obesity is not evenly distributed, and the story has always been that "exercise doesn't matter, what you eat controls your weight" so things like biking vs driving should have a relatively small effect. But people wanted to turn it into a moral hazard, and they did. Fat people have always been a socially-acceptable target to punch down on. "I'm actually helping them, you see".
- hollerith 3y ago
  You misunderstand the details, but your overall point is correct, IMO.
- elevatedastalt 3y ago
  CICO looks like dumb advice ONLY if you think it to mean that you should be literally summing the nutritional labels of the foods you consume and whatever calorie estimates your smartwatch shows you and treat it as gospel. Both the CI and CO numbers can have very large error margins, however, the fact that their difference, if leading to a caloric deficit, will cause weight-loss is irrefutable truth. If you do a diet for 14 days and have no change in weight, it just means you need to reduce consumption more. CICO isn't unfair because it's incorrect. It's unfair because for some people following CICO comes trivially, while for others it's literally the hardest thing they will ever do in their lives. And that's why I do sympathize with people who find it hard to lose weight. You are fighting against your most primal instincts (the desire to eat). But that doesn't mean CICO is incorrect.
  - xk_id 3y ago
    oh thank god someone else put in the effort to type this, so I didn't have to. yes, this view is 100% correct.
- thefz 3y ago
  CICO is thermodynamics. People argue against it because it means that to lose weight, you either burn more or, drum roll, get in less. There is really no way out of physics, argue all you want.
- xboxnolifes 3y ago
  Dynamic bounds doesn't mean no boundary. Maybe we viewed different communities, but I rarely came across people who thought calorie counting was 100% accurate. Human bodies are complex systems. But, calories in is still an upper bound, and calories out is still roughly accurate when tracking exercise. The big contention is the middle part.
Wowfunhappy 3y ago
But what is the downside? (I mean, other than weight gain.) You just get more energy for free? Why doesn't the body use less energy by default?
- xk_id 3y ago
  The physiological adaptations to caloric restriction in general are extremely broad and not all are related to the tradeoff in thermogenesis. But to answer your question, you basically get cold much more easily, basically all the time. As for why the body isn't always operating as efficiently as it does on CR: it's possible that the "default" state we are in today, due to caloric overabundance, is actually a hyper-active state, characterised by excessive protein synthesis, tissue hypertrophy and libido, among other things. These are all very costly in terms of metabolic resources. When fewer calories are available, developmental processes slow down, metabolism switches to catabolic autophagy (which has the benefit of recycling old and damaged organelles) and reproductive function is deprioritised, in favour of optimising survival. The evolutionary basis is to ensure survival, until comfortable sustenance is found again, so that reproductive concerns can be resumed.

xyzelement 3y ago

// How exactly is your body able to accomplish the same task with less energy? Maybe a useful analogy is that my hybrid SUV and a v8 Range Rover sport consume very different amount of gas even for driving the same distance at the same speed.