Muscles cost energy to maintain. We evolved in an environment of scarcity, where you never knew where your next meal was going to come from. So from your body’s perspective, if you’re not actively using your muscles they’re just costing unnecessary energy, and your body will break them down to save on energy.
Maintaining muscle costs energy, so if we don’t need it we lose the muscle. We do however retain the nuclei required to rebuild the muscle cells – which makes rebuilding said muscle easier. The hypothesis is that this ability evolved to handle seasonal variability in activity levels and food supply. Essentially put on muscle in summer when game is plentiful and lose it in winter when conserving energy is a greater priority.
At least not really, but if you don’t use a muscle for long enough your body decides that its not worth the extra calories to maintain it. Calories were rare when we evolved so our bodies had to get really good at sending calories where they were needed.
A person from Stone Age time traveling to today would be exactly equal to us genetically. Our bodies are outdated. Muscles require more calories each day to maintain. Although people struggle to reduce calorie intake nowadays, people struggled to get enough calories back then. Therefore, the body would get rid of calory-intensive muscles when they are not needed.
Modern people go from active fitness training to ZERO activity, just sitting in a chair the entire day. Evolution had nothing like that to adjust for. In ancient times becoming inactive would still include hours of walking each day, lifting things, bending, getting up and down a lot. The only time an ancient person would be reduced to not getting up at all would be if they were so injured or ill they were bedridden.
The body adapts to the environment pretty rapidly because the environment that humans lived in also could change quickly. Adaptations towards “fitness” are generally costly and so the body won’t maintain those adaptations unless needed.
It’s a reactive system and a lot of it is built around energy balance. Famine was somewhat common in the prehistoric past, and even the historic past, and so the body evolved was of adjusting itself to avoid starvation.
There’s also a different lens that you can see a “fitness” adaptation, where it is meant more for protection as opposed to increasing “fitness”. Like muscles grow and get stronger because them being put under those stresses is a signal that something bad could happen, like getting crushed or the muscles tearing.
The body gets really efficient with nutrients when dieting more because it has to in order to keep everything functioning properly.
I put air quotes around fitness here because the concept gets muddy. Physical fitness is different than survival fitness, and you have to be careful not to intertwine them. Someone who is more physically fit may be more likely to survive in one environment, and less in another. Sometimes physical fitness doesn’t matter all that much.
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Muscles cost energy to maintain. We evolved in an environment of scarcity, where you never knew where your next meal was going to come from. So from your body’s perspective, if you’re not actively using your muscles they’re just costing unnecessary energy, and your body will break them down to save on energy.
Maintaining muscle costs energy, so if we don’t need it we lose the muscle. We do however retain the nuclei required to rebuild the muscle cells – which makes rebuilding said muscle easier. The hypothesis is that this ability evolved to handle seasonal variability in activity levels and food supply. Essentially put on muscle in summer when game is plentiful and lose it in winter when conserving energy is a greater priority.
We don’t?
At least not really, but if you don’t use a muscle for long enough your body decides that its not worth the extra calories to maintain it. Calories were rare when we evolved so our bodies had to get really good at sending calories where they were needed.
Who to you this? You might be asking this question based on anecdotal evidence.
A person from Stone Age time traveling to today would be exactly equal to us genetically. Our bodies are outdated. Muscles require more calories each day to maintain. Although people struggle to reduce calorie intake nowadays, people struggled to get enough calories back then. Therefore, the body would get rid of calory-intensive muscles when they are not needed.
Modern people go from active fitness training to ZERO activity, just sitting in a chair the entire day. Evolution had nothing like that to adjust for. In ancient times becoming inactive would still include hours of walking each day, lifting things, bending, getting up and down a lot. The only time an ancient person would be reduced to not getting up at all would be if they were so injured or ill they were bedridden.
The body adapts to the environment pretty rapidly because the environment that humans lived in also could change quickly. Adaptations towards “fitness” are generally costly and so the body won’t maintain those adaptations unless needed.
It’s a reactive system and a lot of it is built around energy balance. Famine was somewhat common in the prehistoric past, and even the historic past, and so the body evolved was of adjusting itself to avoid starvation.
There’s also a different lens that you can see a “fitness” adaptation, where it is meant more for protection as opposed to increasing “fitness”. Like muscles grow and get stronger because them being put under those stresses is a signal that something bad could happen, like getting crushed or the muscles tearing.
The body gets really efficient with nutrients when dieting more because it has to in order to keep everything functioning properly.
I put air quotes around fitness here because the concept gets muddy. Physical fitness is different than survival fitness, and you have to be careful not to intertwine them. Someone who is more physically fit may be more likely to survive in one environment, and less in another. Sometimes physical fitness doesn’t matter all that much.