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Weight training doesn't make your muscles bigger, it inspires your body to make your muscles bigger. So my question has always been, if having bigger muscles is

by Aron 9y ago

Weight training doesn't make your muscles bigger, it inspires your body to make your muscles bigger. So my question has always been, if having bigger muscles is good why doesn't the body just do it? It certainly has to be aware that I'm operating with a calorie surplus.

maxcan 9y ago
Simply maintaining muscle mass requires a considerable amount of calories. Our bodies evolved to function with the least calories possible. So, if you aren't using your muscles often, the body will catabolize muscle to save energy. If you are using your muscles, and thus signaling to your body that you need more of them, your body will devote energy to hypertrophy and increase muscle mass. The current regime of near universal caloric surplus is not something our ancestors ever faced and evolution left us very little tools to deal with instinctively.
- thaumasiotes 9y ago
  > The current regime of near universal caloric surplus is not something our ancestors ever faced and evolution left us very little tools to deal with instinctively. This depends on your ancestors. Demographics with a long history of agriculture are much less vulnerable to diet-induced diabetes than, say, native Americans are. Some people will eat to gorging when faced with more food than they can eat, and some won't.
  - cbanek 9y ago
    That's super interesting about demographics with a long history of agriculture. Do you have any links for further reading on that?
    - barry-cotter 9y ago
      https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1323307/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1323307/ Diabetes and Mexicans: Why the Two Are Linked https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1932342/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1932342/ Diabetes Mellitus: A “Thrifty” Genotype Rendered Detrimental by “Progress”?
- Aron 9y ago
  How many calories do you think it takes [to maintain] +1 lb of muscle mass, with same activity levels? [Hint: It's not the broscience 50]
cma 9y ago
Probably a calorie surplus is more efficiently stored as fat than as muscle (which consumes considerable extra calories too). And most food crisis events maybe aren't remedied with brute strength, especially if you hadn't been using strength before the crisis to achieve your main foodstuffs. (But it could be many other reasons too when you factor in sexual selection, etc.)
DrScump 9y ago
Genetics and epigenetics. If muscle isn't needed and used, it's expensive to maintain.
dnackoul 9y ago
Because muscles take energy to power and fat is storage. In the non-modern world where food was scarcer it wasn't always advantageous to increase in muscle size and therefore caloric needs. Better to carry some fat around in case you don't find food for a while.
- Aron 9y ago
  I agree that this is the shape of the answer, but I think that fat being preferential to muscle as a calorie store leaves not a lot of room to believe that muscle had substantial other advantages to health. Now of course, it might not be having the muscle that is healthful, but the activities involved in creating it.
innerpeace1 9y ago
Bravo, spoken like a true geek, if only evolution was as simple as building machines.
- dpark 9y ago
  Evolution is building machines. What is often missed is that the machines that survive best across many scenarios may not excel in most scenarios. You can build a robot that moves 60mph on wheels but it can't take the stairs. Evolution could have built humans that naturally carry far more muscle, but those same humans would die massively in the event of a famine.
  - Aron 9y ago
    In a famine, they can consume their muscles as calories.
    - Volundr 9y ago
      The return on consuming muscles is much lower than consuming fat. Thus we retain fat not musculature.
- FullMtlAlcoholc 9y ago
  Evolution does build machines. It is a master of nanotechnology.
garraeth 9y ago
Even if you are operating with a calorie surplus, you'd need to eat an optimal mix of nutrients to maintain extra muscle. Most people (most likely) cannot simply ramp up amounts of what you currently eat. For example, if you suddenly require 5000 c/day, you cannot simply eat more pizza, MT Dew, etc. You have to eat 5000 c/day of nutrient rich food. Your muscles do not only require calories. This is actually very hard to do (imagine how much actual food volume you have to process)! You also need many more macronutrients to keep things going (all that extra food needs to be processed), and clean (significantly more waste byproducts produced). Your cardiovascular system needs to grow in conjunction with the extra muscle -- it must keep up. As does your skeletal (bones, ligaments/tendons).
- ec109685 9y ago
  Which nutrients are pizza missing for building muscle? The problem with pizza is that it is way too easy to over indulge, but I don't think it is lacking "nutrients".
  - Daishiman 9y ago
    Fiber for improved intestinal health, and probably a boatload of micronutrients.
    - ec109685 9y ago
      Crust has fiber.
  - tejohnso 9y ago
    Protein. Pizza is a high carb dish in most cases. If you're getting a whole chicken breast worth of chicken per two or three slices, that's a different story. But in general it's mostly a bunch of white bread with some tasty sauce on it.
    - ntsplnkv2 9y ago
      Pizza has cheese which has a decent amount of protein in it. Lots of pizzas also have meat toppings as well.
amelius 9y ago
A related question would be: why doesn't my body dump all the fat, since I'm eating a surplus of calories anyway?
- Aron 9y ago
  Presumably because carrying surplus fat has minimal cost relative to the evolutionary likelihood of famine. This is more obvious than the muscle scenario. For muscle, prior to the famine you get to do cool things like punch your neighbor and do pull ups. During a famine, you could consume your muscles as calories. Where is the cost?
  - bluedino 9y ago
    If your body fat percentage is too low, you'll run into side effects (including reproductive ones)
  - dpark 9y ago
    During a famine your fat neighbor will survive longer. Storing fat is more efficient than building muscle. Maintaining fat is more efficient than maintaining muscle. And metabolizing fat is more efficient than metabolizing muscle. So while it's cool that you can do pull-ups, your fat neighbor will easily outlast you in a famine unless you're willing to eat him.
- _chris_ 9y ago
  why doesn't my body dump all the fat, since I'm eating a surplus of calories anyway? That's a great research question. Normally, the body tries to maintain a happy "set point" of fat. However, different genetic populations (who may have historically gone through more famine) are more inclined to save fat than dump it relative to others. Researchers suspect that there is some mechanism that may be going awry due to our modern diet/lifestyle. Fat makes a protein called leptin; the more leptin in our body, the fatter we must be. So why is our body not properly measuring how much leptin is in our bloodstream and thus thinking it is skinnier than it really is? Answer that and you will both win a Nobel Prize and become a very rich person.
eberkund 9y ago
Simply put: your body knows you are operating at a caloric surplus NOW. But it can't assume you will be operating at a caloric surplus for the indefinite future. Your body doesn't want to behave like a professional athlete who spends all the money from their first contract only to have a career ending injury and wind up broke.
ChemicalWarfare 9y ago
muscles DO get bigger when you consume more calories then what your body requires for "maintenance". except of course unless your testosterone levels are exceptionally high most of those calories would go into fat storage. you might know that this calorie surplus will last "forever" but your body doesn't so to speak so it's choosing a safe bet survival strategy-wise.
tybit 9y ago
I think it effectively operates under the heuristic of build only as much muscle as needed(which is why the signals(hormones) are needed), store excess as fat. That makes sense if starvation is the largest risk shaping evolution, but this is all just armchair biology.
oh_sigh 9y ago
Because your body deems big muscles as relatively worthless if you don't need them. They are a big energy sink so it makes sense. Also, being muscular increases your basal metabolic rate, so not only does it take energy (which may not be available) to grow them, but you also spend more energy simply existing with more muscle mass.

by Aron 9y ago

maxcan 9y ago

Simply maintaining muscle mass requires a considerable amount of calories. Our bodies evolved to function with the least calories possible. So, if you aren't using your muscles often, the body will catabolize muscle to save energy. If you are using your muscles, and thus signaling to your body that you need more of them, your body will devote energy to hypertrophy and increase muscle mass. The current regime of near universal caloric surplus is not something our ancestors ever faced and evolution left us very little tools to deal with instinctively.

thaumasiotes 9y ago
> The current regime of near universal caloric surplus is not something our ancestors ever faced and evolution left us very little tools to deal with instinctively. This depends on your ancestors. Demographics with a long history of agriculture are much less vulnerable to diet-induced diabetes than, say, native Americans are. Some people will eat to gorging when faced with more food than they can eat, and some won't.
- cbanek 9y ago
  That's super interesting about demographics with a long history of agriculture. Do you have any links for further reading on that?
  - barry-cotter 9y ago
    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1323307/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1323307/ Diabetes and Mexicans: Why the Two Are Linked https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1932342/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1932342/ Diabetes Mellitus: A “Thrifty” Genotype Rendered Detrimental by “Progress”?
Aron 9y ago
How many calories do you think it takes [to maintain] +1 lb of muscle mass, with same activity levels? [Hint: It's not the broscience 50]

cma 9y ago

Probably a calorie surplus is more efficiently stored as fat than as muscle (which consumes considerable extra calories too). And most food crisis events maybe aren't remedied with brute strength, especially if you hadn't been using strength before the crisis to achieve your main foodstuffs. (But it could be many other reasons too when you factor in sexual selection, etc.)

DrScump 9y ago

Genetics and epigenetics. If muscle isn't needed and used, it's expensive to maintain.

dnackoul 9y ago

Because muscles take energy to power and fat is storage. In the non-modern world where food was scarcer it wasn't always advantageous to increase in muscle size and therefore caloric needs. Better to carry some fat around in case you don't find food for a while.

Aron 9y ago
I agree that this is the shape of the answer, but I think that fat being preferential to muscle as a calorie store leaves not a lot of room to believe that muscle had substantial other advantages to health. Now of course, it might not be having the muscle that is healthful, but the activities involved in creating it.

innerpeace1 9y ago

Bravo, spoken like a true geek, if only evolution was as simple as building machines.

dpark 9y ago
Evolution is building machines. What is often missed is that the machines that survive best across many scenarios may not excel in most scenarios. You can build a robot that moves 60mph on wheels but it can't take the stairs. Evolution could have built humans that naturally carry far more muscle, but those same humans would die massively in the event of a famine.
- Aron 9y ago
  In a famine, they can consume their muscles as calories.
  - Volundr 9y ago
    The return on consuming muscles is much lower than consuming fat. Thus we retain fat not musculature.
FullMtlAlcoholc 9y ago
Evolution does build machines. It is a master of nanotechnology.

garraeth 9y ago

Even if you are operating with a calorie surplus, you'd need to eat an optimal mix of nutrients to maintain extra muscle. Most people (most likely) cannot simply ramp up amounts of what you currently eat. For example, if you suddenly require 5000 c/day, you cannot simply eat more pizza, MT Dew, etc. You have to eat 5000 c/day of nutrient rich food. Your muscles do not only require calories. This is actually very hard to do (imagine how much actual food volume you have to process)! You also need many more macronutrients to keep things going (all that extra food needs to be processed), and clean (significantly more waste byproducts produced). Your cardiovascular system needs to grow in conjunction with the extra muscle -- it must keep up. As does your skeletal (bones, ligaments/tendons).

ec109685 9y ago
Which nutrients are pizza missing for building muscle? The problem with pizza is that it is way too easy to over indulge, but I don't think it is lacking "nutrients".
- Daishiman 9y ago
  Fiber for improved intestinal health, and probably a boatload of micronutrients.
  - ec109685 9y ago
    Crust has fiber.
- tejohnso 9y ago
  Protein. Pizza is a high carb dish in most cases. If you're getting a whole chicken breast worth of chicken per two or three slices, that's a different story. But in general it's mostly a bunch of white bread with some tasty sauce on it.
  - ntsplnkv2 9y ago
    Pizza has cheese which has a decent amount of protein in it. Lots of pizzas also have meat toppings as well.

amelius 9y ago

A related question would be: why doesn't my body dump all the fat, since I'm eating a surplus of calories anyway?

Aron 9y ago
Presumably because carrying surplus fat has minimal cost relative to the evolutionary likelihood of famine. This is more obvious than the muscle scenario. For muscle, prior to the famine you get to do cool things like punch your neighbor and do pull ups. During a famine, you could consume your muscles as calories. Where is the cost?
- bluedino 9y ago
  If your body fat percentage is too low, you'll run into side effects (including reproductive ones)
- dpark 9y ago
  During a famine your fat neighbor will survive longer. Storing fat is more efficient than building muscle. Maintaining fat is more efficient than maintaining muscle. And metabolizing fat is more efficient than metabolizing muscle. So while it's cool that you can do pull-ups, your fat neighbor will easily outlast you in a famine unless you're willing to eat him.
_chris_ 9y ago
why doesn't my body dump all the fat, since I'm eating a surplus of calories anyway? That's a great research question. Normally, the body tries to maintain a happy "set point" of fat. However, different genetic populations (who may have historically gone through more famine) are more inclined to save fat than dump it relative to others. Researchers suspect that there is some mechanism that may be going awry due to our modern diet/lifestyle. Fat makes a protein called leptin; the more leptin in our body, the fatter we must be. So why is our body not properly measuring how much leptin is in our bloodstream and thus thinking it is skinnier than it really is? Answer that and you will both win a Nobel Prize and become a very rich person.

eberkund 9y ago

Simply put: your body knows you are operating at a caloric surplus NOW. But it can't assume you will be operating at a caloric surplus for the indefinite future. Your body doesn't want to behave like a professional athlete who spends all the money from their first contract only to have a career ending injury and wind up broke.

ChemicalWarfare 9y ago

muscles DO get bigger when you consume more calories then what your body requires for "maintenance". except of course unless your testosterone levels are exceptionally high most of those calories would go into fat storage. you might know that this calorie surplus will last "forever" but your body doesn't so to speak so it's choosing a safe bet survival strategy-wise.

tybit 9y ago

I think it effectively operates under the heuristic of build only as much muscle as needed(which is why the signals(hormones) are needed), store excess as fat. That makes sense if starvation is the largest risk shaping evolution, but this is all just armchair biology.

oh_sigh 9y ago

Because your body deems big muscles as relatively worthless if you don't need them. They are a big energy sink so it makes sense. Also, being muscular increases your basal metabolic rate, so not only does it take energy (which may not be available) to grow them, but you also spend more energy simply existing with more muscle mass.