So, to start out with. I've got a character with an alien biology and has an accelerated healing factor. Nowhere near the likes of Wolverine, or Deadpool but better than a regular Humans and allows them to survive more than most people would.

The basic gyst of how this accelerated healing factor works is: Their species has a locked away gene in their DNA that allows for the excessive and rapid production of stem cells, which in this characters particular case were gifted with the capability of using this. Stem cells flood the wounded areas (only in extreme cases. Smaller wounds such as cuts will heal normally much like how our own body heals smaller wounds slower)

They are female 178cms in height 265lbs in weight (mostly muscle and due to heavy/sturdier bones) And have a slim somewhat curvy body shape. And ofc, alien.

So, I have a few questions;

What sort of food/calorie intake would realistically be expected of them to make this work?

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    $\begingroup$ Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. $\endgroup$
    – Community Bot
    Mar 13, 2022 at 17:13
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    $\begingroup$ Please remember that we're here to help you solve problems you encounter worldbuilding not build your world for you. Unless you explain how an accelerated healing factor works in your world we're not going to be able to answer the multiple questions you've asked. Also keep in mind that we have a strict limit of one question per post restriction on this site. I currently see at least 4 separate questions. Can you edit this to provide details about how your take on an accelerated healing factor works and restrict the scope to one specific question. $\endgroup$
    – sphennings
    Mar 13, 2022 at 17:33
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    $\begingroup$ @ConnorDawn welcome.. tip: there are still 2 questions now. Agree with sphennings, better split your question in two questions. Remove the second question, change the title.. and make a separate question of the limits thing. $\endgroup$
    – Goodies
    Mar 13, 2022 at 18:32
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    $\begingroup$ @Punintended well iirc stem cells are stored in the bone marrow, no? And to some extent I'd probably get all hand wavey "it's alien stem cells" but that feels a bit lazy and goes against my "realism approach" $\endgroup$ Mar 13, 2022 at 18:49
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    $\begingroup$ weird to have height in cm and weight in lbs $\endgroup$
    – Allan
    Mar 13, 2022 at 18:58

2 Answers 2


As you showed they have some sort of active response to a trauma, in a form of emission of stem cells. This could mean that their normal food requirement is not that much bigger than a human would have.

About their stem cells emissions, it could be calculated from biomass that is required for the healing process. All of the damaged tissues will likely get dissolved by the body, and new ones are built in place. In animals growing 1kg of biomass takes about 10kg of food. Anywhere from 2 to 25. https://cricketpowder.com/sustainability/

Another case to consider is pregnancy. When body is making a baby, we can just look at it from the prespective of making a new biomass from food. Total additional food intake is about 24 000 calories, and newborn weight is about 3.3kg, placenta weight 0.6kg, additional uterus weight 1kg. Thats at least 4.9kg of biomass carefully created for a task, using only 8.3kg of beef as a food source. Hmmm... I expected it to be much more. Probably something is off with the additional food intake calculation. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3530253/ https://www.whattoexpect.com/pregnancy/calories-diet/ https://parenting.firstcry.com/articles/uterus-during-pregnancy-everything-you-need-to-know/

But you get the idea. To calculate how much of biomass is transformed, and use a coefficient of 2...25 to get amount of food required.

If your alien is hit with a bullet, that makes a kilogram of flesh non-functional, your alien would need to eat 2...25 kg of food, at least. Depending how careful the healing process is adapted to be low usage. Thats assuming no blood loss, no infection. Blood loss can be calculated the same way, 1kg of blood (100kcal) is not that far of 1kg of meat (290kcal). Infection can do massive damage to the body and require tens of kg of food. Thin cuts, if wound is closed while healing, can be cheap to fix, not a lot of biomass is required within a thin cut.

Blood loss is likely to be the main danger, in case of a trauma. It can be somewhat fixed with slightly different circulation system. In particular well developed bypass blood vessels, like some humans do. Another benefit is muscles that can contract and stop the blood flow in certain vessels, like lizards do. Then unless this alien is chopped into small pieces, it will be fine, if it has food. https://news.yale.edu/2011/09/30/study-abundance-bypass-vessels-key-surviving-coronary-artery-disease https://www.lizards101.com/lizards-lost-tail/

Open wound is prone to infections. So much so that it makes sense to add about equal amout of white blood cells to the stem cells, to always patrol the damaged area, to quickly form pus, before more tissue is damaged by the microbes. Considering the scale and time requirements you cant allow the wound to dry, that is an easy way to reduce bacterial load. So your aliens' wounds will be constantly wet and will constantly drip pus while they heal. Extremely wasteful in terms of energy, but if your aliens can afford to eat that often, and can digest this much food, its okay. Pus, partially made of white blood cells, would weigh about as much as the damaged flesh. And is as expensive to make.

All together, blood loss, pus and the formation of new tissue, consider the cost to about triple, from 2...25 to 6...75 kg of food per kg of damaged tissue. For the case of open wound, wet wound, non sterile healing process.

Keep in mind, that even if food is present, ability to digest the food is limited. Humans cant eat more than about 3kg of beef equivalent of calories per day, simply because the digestion system isnt powerful enough. https://www.quora.com/Digestion-Is-there-a-maximum-amount-of-calories-a-human-body-can-absorb-in-a-limited-amount-of-time?share=1

Alltogether, assuming 30kg of food for 1kg of damaged tissue, a medium sized gunshot wound, and human-like digestion system, it will still take 10 days to heal it, simply because of food intake limitation.

Even faster healing rate would really push the limit of getting rid of the heat, using special food only because normal food cant be digested fast enough, not even cooked food.

All of this assumes limitless amount of water available... In nature water is often a limiting factor for such extreme level of activity.


Circulation problems.

/Stem cells flood the wounded areas/

So the healing supply must arrive where it needs to be via the circulatory system.

If there is a wound that is bleeding so fast that the stem cells can't stop and get off, that would be a problem. You can invoke faster clotting, contractile arteries etc. For regular humans it is possible to rapidly bleed out from an arterial wound in a place diffcult to compress (armpit, groin, neck). That could be problematic for your character too.

A bigger problem would be a wound that itself shut down the circulatory system. That would be a wound to the heart either penetrating the heart or (and better for a fiction, I think) a wound causing cardiac tamponade - this prevents the heart from filling with blood and so blood pressure falls. There are some edgy first aid maneuvers that could address tamponade which could be good for your fiction.

5 foot 6 and 265 lbs will be curvy indeed! As regards adequate nutrition your character is doing fine; no advice on that front.

  • $\begingroup$ Thank you! Yeah I had considered the whole heart thing or holding a wound open to force bleeding out being a fatility, and on the 'curvy' she's like, relatively slim. Curvy meant more so in the hip area. She's about same stature as uh, unsure of a real world equivalent. Scarlet Johnson? $\endgroup$ Mar 13, 2022 at 18:54
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    $\begingroup$ Hey Connor. I love that green check but maybe you should take it back and give an upvote instead. Just for now. There could (very easily) be better answers that this that come along over the week. $\endgroup$
    – Willk
    Mar 13, 2022 at 19:09
  • $\begingroup$ Gotcha! It won't let me until I've got 15 rep but I will when I do! $\endgroup$ Mar 13, 2022 at 19:11

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