I went to the doctor the other day, for the typical autoimmune issues I’ve mentioned on this blog. While I was talking to one of the doctors about my issues, they offhandedly confirmed my feelings with a “we noticed your eosinophils were quite high.” I’d always suspected that, but I hadn’t had any tests to confirm, and although it was likely I just wanted to confirm medically before I started claiming something… Although googling it it’s almost a fact that if you have autoimmune issues you’ll have high eosinophils, so I guess I could have claimed it anyway.

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But as I was leaving the doctor’s office, it occured to me that maybe this is why at least some shifters are the way they are. A symptom of my autoimmune condition is that I don’t get cold; when it’s flaring I could be out in sixty or even fifty degree weather and still be hot. A lot of shifters also describe this same symptom, and while it’s not always tied to being a shifter (many conditions are tied to high eosinophils) enough shifters have mentioned it that I think there may be something there. Eosinophils are white blood cells that are responsible for a bunch of functions in the body, including wound healing and chemical signaling.

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And then later on it occurred to me that with this information, maybe shifting is less like breaking a bone and more like self-cannibalism? Eosinophils in eosinophilic diseases attack the human body and its organs, but it doesn’t outright cause damage the way a broken bone or serious physical injury might. I’ve seen therians try to disprove shifting by using calculations for injuries as a gotcha - the logic being that if you were to injure yourself a thousand times over you’d die from shock or an energy deficit. But if shifting isn’t a critical injury, and your calorie source is yourself, then you can bypass those restrictions.

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So I decided to do some calculations. I found an academic journal which goes into the calories of an average adult male organ by organ. Total calories of an adult male is around 143,771.33cal, and their weight is around 65.99kg. Now, googling how long it takes to heal an injury (I know I said shifting isn’t like healing an injury but unfortunately there isn’t any data on how long it takes to heal from eosinophilic diseases and the calories burned from them) it would seem as if it takes 30cal per kilogram of weight. 30cal × 65.99kg = 1,979.7cal/kg. (I’m going to treat the entire body as if it is a giant “wound” instead of tiny unspecified cuts and injuries.) Different sources say that the human body is composed of 40% skeletal muscle, 18-24% fat, and 14% bone (for men). I’m assuming the rest is things like cartilage, keratin (hair, nails), smooth muscle, organs and other bodily byproducts that don’t fit into this.

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So assuming our 65.99kg man has 40% skeletal muscle, 18% fat, 14% bone, and 28% everything else, we can take the percentages of 1,979.7cal/kg, since I’m assuming that the 30cals would be distributed evenly around the body, or to the parts that need it the most. 40/100 × 1,979.7cal/kg = 791.88cal/kg, 18/100 × 1,979cal/kg = 356.346cal/kg, 14/100 × 1,979cal/kg = 277.158cal/kg and 28/100 × 1,979cal/kg = 554.316cal/kg. We’ll really only need skeletal muscle and bone, since as far as I know fat isn’t modified (it may be redistributed on the body or used, but it itself doesn’t appear to be touched by the shifting in the same way), and hair, nails, etc. simply don’t have a rate attached since they tend to be negligible. Organs may not be severely affected as well (if they were, shifting would kill people immediately) and I’d have to assume they’re largely untouched.

(Note that for me and other shifters I’ve talked to, bones do not break, they moreso flow? into an area. This is why I’m not calculating for the breaks of a bone or anything like that, there’s nothing to break.)

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Muscle damage is graded on a severity of 1 to 3, with grade 3 injuries taking months to heal and grade 1 a few weeks. I chose a grade 2 injury to represent shifting since it would most likely mimic a severe injury, but not to the point where you couldn’t use the muscle or function with it. Grade 2 injuries take at most 16 weeks to heal, so 791.88cal/kg of muscle × 7 days = 5,543.16cal/kg per week so then 5,543cal/kg × 16 weeks = 88,690.56cal/kg. Bone takes 12 weeks to heal at the latest, so 277.158cal/kg × 7 days = 1,940.106cal/kg and 1,940.106cal/kg × 12 weeks = 23,281.272cal/kg.

88,690.56cal/kg skeletal muscle + 23,281.272cal/kg bone + 554.316cal/kg everything else + 356.346cal/kg fat = 112,882.494cal/kg total to heal bone and muscle, or reform a shifter’s body.

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Calories of adult male (143,771.33cal) - calories of “shifted” male (112,882.494cal/kg) = 30,888.836cal/kg left over, meaning that if you were to shift using your body as energy, you’d have 30,888.836cal/kg to spare. Now, if we were talking about calories you need to ingest needing 112,882 of them would be an unreasonable amount, unless you healed over a period of weeks or days. However, since the body is our energy source, it will be the source of calories used while shifted, and we’ll assume the process is sped up.

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The human body is imperfect at digesting calories - off the top of my head I’ve heard 65% of what we eat is actually used as energy, with the rest being burned while processing those calories or simply lost while processing, but more recent estimates have it at 95%. I know reusing parts of the body isn’t exactly like digesting external matter through your stomach, but assuming it’s similar enough, 95/100 × 112,882.494cal/kg = 107,238.369cal/kg so 112,882.494cal/kg − 107,238.369cal/kg = 5,644.1247cal/kg lost. So transforming would (assuming you were efficient at digesting matter) cause you to lose around 5,000 calories, which actually lines up with the claims I’ve heard from other shifters, who say they get really hungry after shifting but not overly so to where they’d need medical assistance or the like. 5,000 is around the amount athletes eat, so it’s not an unreasonable amount to build back either.

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Going a little bit further… If that’s how many calories athletes burn, the body temperature of athletes in action should be applicable to shifting, right? A body temperature above 40°C is dangerous for long periods of time, because it denatures proteins and destroys the body. But it would seem athletes regularly go past that without necessarily suffering ill effects, indicating that at least on some level the body can handle high temperatures short term. (If you’re disabled however, the risks increase due to physiological differences, so this doesn’t apply across the board.)

So shifting (if my math is right and all this is applicable to the real world) should typically lead to a calorie deficit of around 5,000 calories, a body temperature above 40°C (but not too far) and exhaustion similar to that of experienced athletes. It does not destroy the body, because everything is in accepted ranges and the body is being “digested” and used as a source of food.

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Feel free to check my work. A lot of the math surrounding this stuff is hard to do because a lot of the values necessary to calculate it have never been studied. I was trying to find the amount of calories hair growth would take even for an average adult human, but hair is considered negligible and the people I’ve come across tend to use sheep’s wool as a replacement, which might distort the calculations a bit. If you have any values for me to work with though, you’re more than welcome to send them to me! I’ll see how I can work them into my calculations, if possible.