it’s going to come as no surprise to anyone when i say that pietro maximoff requires an absurd number of calories to maintain, well, living. and i mean absurd number as in, i wont give you a real estimate because frankly, i don’t know. i just know it’s a lot. definitely more than you or i could fathom ever coming close to consuming.
now, because peitro’s super speed stems from his body itself & his genetic mutation instead of outside forces, this makes his body quite literally designed for speed. he isn’t just running fast, he is built for this. pietro is mutated in every way. between having a faster metabolism, to having a mutated thyroid for increased heart rate & oxygen flow, to faster synapse firing in his brain and even a degree super strength in the lower half of his body (he can lift about a ton with his thighs, fam). he’s a mutant. ( those are just a few examples and i’ll probably write a detailed headcanon about it all later, but for now you get the picture. ) his genetic mutations are what allow him to run the way he does and function.
since pietro’s metabolism is so fast, he metabolizes about 90% of his caloric intake, which means he only expels 10% of it as waste. and whatever fatigue toxins produced in his muscles during a run, are spent through his breathing. now, his body obviously annihilates the food he consumes, which means he can and will easily eat his body weight in food in just one day, and then some. i joke that he’s like a humming bird all the time, but he really is. ( & male humming birds can consume up to 1 1/2 times their weight in a single day).
now, even if we take this increased caloric intake into consideration and we’re pretending he eats exactly what he needs to at all times, pietro’s body would still need to be able to manage how much is actually used while running. because if he eats 140 cheeseburgers & then goes for a run, but burns those calories in the 3 seconds it takes him to reach mach 4, that doesn’t help anything. so, i would say it’s a safe bet that his body operates on more than just caloric intake and does not rely solely on food as a form of energy to produce his speed.
here’s why; when pietro runs, there’s a very high level of energy emitted. in reality, if he ran past you at a mach 10 speed, he would flash boil the surrounding air to about 800 degrees F and (unintentionally) launch nearby objects at you at about the same force as a bullet fired from a gun. you’d die. of course, in the comics he doesn’t do that, the air around him does heat up and the ground/water/whatever beneath him is certainly disturbed/disrupted, but he puts off no where near the level of energy he should. i’m personally going to say that this is because he metabolizes the energy he produces while running, which in turn, also assists in fueling his speed. this is why he doesn’t burn out the way most people do and why he doesn’t need to stop and eat a mega ton of calories after breaking the sound barrier for a just few seconds. this would also explain why he doesn’t obliterate everything in his path when he tears through NYC at well over that speed, because he’s not actually expelling all of that energy: he’s also metabolizing it. pietro maximoff is his own speed conduit.
and it’s canon that he can stabilize & destabilize molecules through touch, though it isn’t something he uses much like, say, tommy. pietro’s molecular stabilization comes into play more heavily while he’s actually performing, he’s capable of stabilizing the objects he runs with (people included), which keeps them from turning into a smoothie at these high speeds. it’s something he’s always done naturally, but if he chooses he can do the opposite and quite literally run someone to a speed educed death. (which he has done to another speedster before, reaching somewhere above mach 10 ALL before a temporarily suspended-in-mid-air clint barton could even hit the ground).
