There are plenty of sex differences in human physiology: Body composition, skeleton, hormones, sexual organs, sensory systems, etc. My question is:

How would it feel for a woman to be placed into a male body and what difficulties she would face when it comes to physiology?

Basically, I want to know if walking, eating, talking, and other normal everyday activities will feel the same or will need some readjustment period. Will differences in hormonal status have noticeable physiological effects? I also wonder if the consummation of marriage is possible.

When possible I would like the answers to focus on what would feel different and in what way. For example, an answer may suggest that walking will become harder because of the changed centre of gravity and for a while this woman in a male body will be moving like a drunk person (not sure if this is correct).


  1. 'Placed into a male body' can be understood as a soul of a genetically XX woman placed into a genetically XY male body (it is a miracle that does not need to be explained). Please assume that the female soul and the male body are compatible and there are no big problems with body functions. Some things may feel weird or different, but everything works fine.
  2. Psychological difficulties (including adjustment to a new gender role) are out of the scope of this question. Please do not concern yourselves with them. If physiological changes (e.g. hormones) cause distinctly different psychological responses it is okay to include them.
  3. While there are some differences between male and female brains, those that would make the premise impossible can be discarded. Please also assume that the female soul has complete and 'natural' control over the body and does not need to relearn how to walk, eat, talk, etc.
  4. If it matters, the woman is an adult, the male body is also a fully developed male body.
  5. The woman has her memories intact.
  6. Please assume that the height and weight of the new male body are approximately the same as the original female body.


I understand the theory of sex differences. I am looking for approximations of how it would actually feel to be in a body of different sex.

It might be easier to understand what I am looking for if you consider this:

You know how to drive a car and you have about 20 years of experience driving a MINI (or some other tiny car). One day your MINI is transformed into a family minivan with 3 rows of seats. You still can drive this minivan, you still can do it more or less safely. However, it feels different: Size, speed, acceleration, driver's seat, etc. The size feels too big or the vehicle feels too clumsy. The speed feels lacking. The acceleration is sluggish. The driver's seat is made of fabric and is cold making you grieve your old leather seats with heating. This new car is okay-ish but it just simply does not feel right.

More notes (in regard to opinion-based, unanswerable, etc.)

  1. Every person has a mental representation of their bodies - body image. As a mental construct, the original body image will be still present when a soul is placed into a new body. Since body image contains knowledge and expectations about the normal functioning of one's body a new body will inevitably create cognitive dissonance and disturbances in body image. Also, since the operation of one's body (with the exception of the automatic functions) consciously and unconsciously relies on body image a newly transported soul may face difficulties.

  2. This question is limited to sex differences in human physiology and their manifestation considering the disparity between the original body image and the new body. The sex differences are relatively well understood and researched, they are limited in number. It is also possible to approximate (and for some of those differences it is even possible to calculate) the specific effects.

  3. For those who are confused by the wording 'how does it feel': Feel in the context of this question is not related to emotions but senses and physical experiences with the only exception of drastic physiological influence on emotions. I am not asking whether it will feel good or bad (that would be opinion-based), I am asking whether the person will feel out of balance due to differences in muscle and fat distribution and if so I ask to approximate how this out-of-balance condition will manifest from the body owner's point of view.

  4. Another reason for asking how does it feel is because I am a woman. There are plenty of things that I do not know, do not understand, or would not even consider (see for example Nosajimiki's answer) due to the fact that my own body is not male. Consider pregnancy, no matter how much you read about the biology of pregnancy or watch videos you would have no idea how it actually physically feels to be pregnant unless you were pregnant yourself or someone who has been pregnant shared their experiences with you.

  5. As for concerns about misgendering, invalidating, or questioning transgender identities, my question does not have anything to do with these topics. I specifically stated that gender identity is out of the scope of this question.

If you need clarifications or additional details, please, ask in the comments.

  • 2
    $\begingroup$ When "placed in a different body" there would be a lot of physiological issues related to different height/weight, different muscle/fat mass, different body proportions and metabolism. Many of those differences have little to do with XX vs XY difference. do you want to lest all of them, or only those directly related to primary sexual characteristics? $\endgroup$
    – Alexander
    Apr 29 at 23:43
  • 1
    $\begingroup$ Soul? if it done by magic then you decide what they do and do not notice. How much is the alteration is there to the neural network, can they see and hear right away or do they they have to relearn their sense organs like a transplant would require? Your going to have to tell us how much alteration she has undergone to mesh with the new body. $\endgroup$
    – John
    Apr 30 at 4:50
  • 3
    $\begingroup$ I am voting to close this question as unanswerable. You are basing this question in the existence of a "soul" or a "conscience" which can be transplanted into a different body like you can change your car. But the analogy is not valid. You must use a steering wheel, and if you learnt to drive in an automatic you may struggle with the gears of a manual car, but I bet you don't know the name of all (if any) of the muscles you have used to type your question. While you can use transgender experiences and people with artificial limbs implanted as a guideline, all the answers here are POB. $\endgroup$
    – Rekesoft
    Apr 30 at 10:28
  • 3
    $\begingroup$ Opinion-based. There is no way to qualify or quantify what differences someone would feel in this scenario, and inclusion of a 'soul' means all the physiological bases of identity are excluded, leaving what I'm not sure. Further I worry this exposes questioner and answerer to accusations of misgendering, invalidating, or questioning transgender identities. $\endgroup$
    – rek
    Apr 30 at 12:41
  • 2
    $\begingroup$ @Otkin No, I accept your premise of exchanging conscience to a new body - that's a staple of sci-fi. Even if souls aren't real, you could go for "conscience", as in "Ghost in the shell" or "altered carbon". The point is that, intrinsically impossible as it is in a site such as worldbuilding.se, StackExchange tries to give "correct" answers to questions, and yours has no possible correct answer - or in other words, there are many possible answers and no way to determine which is the most correct one. The most we can offer you from here is "it would feel the way you want in your story". :) $\endgroup$
    – Rekesoft
    May 4 at 7:26

Basically, I want to know if walking, eating, talking, and other normal everyday activities will feel the same or will need some readjustment period.

Some adjustment period will most likely be needed. See also this question and some of the answers thereto, the upshot of which is that if your body undergoes any sort of major change, there is most likely going to be some adjustment period. Or, simply consider the sometimes awkwardness of children and adolescents whose bodies are still changing on a daily basis.

Consider also motor problems experienced by people after an injury or period of inactivity. Especially consider the process by which amputees learn to control an artificial limb. A lot of the motor skills adults take for granted depend on practice and having a consistent "platform".

For that matter, even "some adjustment period" may be wildly optimistic. Unless you somehow arrange that all the nerve mappings are exactly the same between the two bodies, something like, say, a brain transplant would leave the poor sap starting from scratch in terms of motor control. Hopefully you at least got the autonomous functions right, or your victim isn't going to live very long, but even if (s)he does, (s)he may be starting with the (lack of) motor skill of a newborn. Actually, not even that much, since even newborns have had some time in the womb to practice.

Will differences in hormonal status have noticeable physiological effects?

Absolutely; just ask anyone undergoing sex reassignment or taking hormone replacement therapy.

I also wonder if the consummation of marriage is possible.

My guess would be "yes". Again, your best bet is to do some research into sex reassignment. Granted, I don't believe we've demonstrated this, but, well, in real life, someone that's undergone SRS is going to be missing "certain key parts", and there are some pretty hefty moral questions that would come into play if one were to try to find "donor parts". However, I'm not aware of any biological reason why this would be an issue.

Further thoughts in response to comments:

If your "female soul" (using quotes because we're now very much in hand-waving territory) isn't used to the mass of the male body, that's likely to be noticeable. Too, the male may have more muscle mass, and even if you assume the male body has similar mass to what the "female soul" expects, the ratios of muscle to fat are likely to be different. At the very least, your "female soul" is likely accustomed to a certain concentration of non-muscular tissue on her upper chest that is going to be missing.

I recommend finding some weights you can strap to your body and trying to move around; that should give you an example of the minimum sort of thing you might expect.

That all said... as soon as you say "the female soul and the male body are compatible" (or, just the fact that you're clearly employing some sort of hand-wavy process that can't be explained by hard science), it seems to me like you've crossed deep enough into "magic" territory that you could also hand-wave away — or exaggerate — such difficulties to whatever extent works for your story.

  • 2
    $\begingroup$ No, my argument is that if you answer a question about magic by asserting that magic doesn't exist, that's not appropriate. You are certainly free to apply your worldview in the absence of other information, but applying your worldview against a stated assumption would be, at best, a frame challenge. (And, yes, it would be inappropriate to tell Terry Pratchett that the world is round.) $\endgroup$
    – Matthew
    Apr 30 at 14:17
  • 1
    $\begingroup$ @Matthew Thank you for the updates to your answer and comments. The premise indeed involves magic or some magic-like process that is left unexplained. I greatly appreciate your kindness and understanding of my question. $\endgroup$
    – Otkin
    May 1 at 0:15
  • 1
    $\begingroup$ @John Science can't explain what part of your brain is responsible for your contiguous 1st person existence. It can explain what parts are responsible for processing experiences, and how they are processed, but by any scientific explanation, your ability to experience the world through your own body should not happen. According to science, you are just a machine, but this only defines processes. How one can BE a machine is thus far unexplained by any theory other than the existence of a soul. What a soul is may be misunderstood, but they are far from disproven. $\endgroup$
    – Nosajimiki
    May 1 at 4:14
  • 1
    $\begingroup$ @John, "soul" is hand-waving for something we can't explain at this time. Perhaps we will eventually prove "souls" don't exist. Perhaps we will prove that they do. We don't know. Meanwhile, it is no less unscientific to assume that they must not exist as to assume that they do. $\endgroup$
    – Matthew
    May 1 at 14:07
  • 1
    $\begingroup$ @John You are mistaking stimulus-response with a first person experience. All we can observe in machines (or other people) is a third person experience. Sure, we understand the aspects of a brain that make it a stimulus-response machine, but what you can not explain with known science is why you are you, and not me or the toaster. While you can assume to a degree that other people have 1st person experiences b/c you have them and we are like you, you do not know where they come from. So, assuming you can create them just by making a stimulus-response machine is a leap of faith, not science $\endgroup$
    – Nosajimiki
    May 3 at 13:37


Other answers have covered most changes. My understanding is that cutting very long hair will have a similar effect (mass change, apparent muscle performance) to many changes. Not having to relearn speech implies that walking will be automatic, but one's choice of path is related to one's perceived dimensions (and politeness).

However, this leaves two considerations - familiar nerves/functions which no longer exist/map to anything in this body, and nerves/functions which now exist and don't map to anything familiar.

Missing structures: The mind seems likely to experience phantom-limb syndrome to some extent. It is also possible that these nerves expected by the mind will be re-mapped to equivalent areas.

New structures: The mind will have difficulty in interpreting any sensation, and is likely to initially have trouble associating nerves with locations. (Ever tried to scratch an itch which moves? Your brain doesn't usually need to know which nerves are affected, since most things affect the whole area.) Assuming that the mind is not adverse to testing, it's likely that they'll take some time to prod different nerves, to learn what sensation corresponds to what location.

Sex organs: You specifically mention this in your question, but the scenario you describe is an idealised test-case for many arguments. Opinions on how much control over these is possible vary, as do the implications for marriage (legal or religious). Individual psychology is a significant factor, and opinions are divided on how much influence the mind has over reflexive attraction.

A baseline: it is possible to influence when an arousal response to occur, but the response is at least semi-autonomous (ex: can occur while asleep). This means that it may occur when unprompted/unwanted, and is likely to occur when prompted/wanted. The exact nature of your transfer will influence the nerve-correspondence between the old and new body, and hence how 'familiar' the mind finds it, but broadly-equivalent structures exist. Physical differences will lead to a degree of adjustment being necessary. However, this may also prompt a more detailed understanding and a greater degree of control.

(Disclaimer: Fish scales are broadly equivalent to hairs, in that they form from the same embryonic structure. This is another area where reams of discussion might be written.)

  • 1
    $\begingroup$ Comments for other answers suggest that many males have a semi-continuous conscious awareness of their reproductive biology (presumably not the internal elements). Previous conversations I've had suggest that this is cultural/psychological rather than biological, but it's possible that I've drawn a non-representative sample. $\endgroup$
    – Anon
    Apr 30 at 3:22
  • $\begingroup$ Rather, are you continuously semi-aware of your arm? Or your foot? Certain male parts, being external, are (depending on clothing) subject to near-constant stimuli. (Yes, there is some degree of "guys are always horny", but it also has to do with physical exposure and that said parts are often being bumped or jostled, or are itching.) OTOH, my own personal experience is not a representative sample, and something as basic as a guy that wears boxers may make a significant difference. $\endgroup$
    – Matthew
    Apr 30 at 13:07

Most of your issues will be hormonal and neurological in nature.

Before you downvote for delving into psychology, it is important to know that psychology and neurology are two different things. If you think of your mind as a computer system, your psychology is the software of your mind, and your neurology is the hardware. While software may try to function the same when installed on two different computers, differences in CPU, GPU, RAM, HD, etc. can cause the software to function very differently, even if it is the same program. The same would be true trying to run one person's mind in another person's body.

The the most noticable difference between the male and female brain is the size of the corpus callosum. A female corpus callosum allows one to hold onto multiple thoughts at a time, transition between thoughts more easily, and associate emotions with logical thoughts better. The male corpus callosum allows one to stay more focused on the task at hand because it creates a weaker connection between emotional and logical processes and is less prone to distractions. The closest experience a woman might have to this prior to the switch would be like taking ADHD medications, or having a mid-brain concussion.

On this level, the woman may find herself feeling trapped inside her own mind, she will be aware of the thoughts she is having, but struggle to express them. She will also likely have feelings that you might describe as "dead inside" because she will no longer be able to process her emotional state the way she is used to. An alternative consequence is that her female software may try pushing it's normal amount of traffic between hemispheres which would make her feel more normal but put her at a major risk for seizures.

For hormonal differences, we all know that she will have more testosterone and less estrogen meaning that she will be more prone to bouts of aggression, right? Not necessarily. As it turns out, estrogen is the hormone responsible for human aggression, and testosterone therapy is often used in women to decrease the anxiety, irritability and aggression associated with PMS. Her endocrine system will push her into a more relaxed, emotionally level state of being than she is probably used to. Between this and the corpus callosum, she will probably feel something comparable to getting stoned, and it will probably take at least a few weeks if not months before she her new reality starts to feel normal to her... assuming it does not trigger any secondary psychological issues like chronic depression.

Kinesiological differences would be minor, but existent

Balance may be a bit of an issue but not for the reasons most people have cited so far. If you've ever put on a backpack or carried a thing that weighs more than a few kilos, you already know that your body is very good at adjusting to distribution of weight issues. The only reason balance would be all that hard is because a woman's pelvis is shaped differently. A woman's legs are turned slightly more outward from a man's so, this will affect her gait. This difference would be more pronounced if the woman has had kids.

Men also have slightly longer arms than women for their height. So, even if the male body is as tall as the female body, she will probably enjoy a slightly longer reach. I say "enjoy" loosely here, because at first it could be off putting. Her Eye-hand coordination would be fine because it relies on the biofeedback of seeing what your hands are doing while you do it, but proprioception based coordination would be difficult because this relies on intuitively knowing where your hand is in space. Children often experience several weeks of clumsiness after major growth spurts of several inches or more; so, your woman may have a similar experience here, but in general, the differences in arm length are just small enough, I don't think it would be overly noticeable.

... then there are those things that guys don't really like to talk about, but I will bring them up anyways because they are scientifically relevant here: her new found gonads will get in the way. A man who knows his own body walks in a certain way that he does not hurt himself, but sometimes men have one of those off days where they literally just walk wrong over too long of a distance and thier tessicals start to hurt. Does not happen to guys very often, but a woman who does not know how to walk with something there is much more likely to struggle with it for a while. Then there is that other thing called "ball-stickage" where you sweat a little and they stick to your leg. If you've ever seen a man walking and he just randomly steps with a single wide step, or kicks out to one side a bit, that is him removing his balls from the side of his leg. To a man this is a normal occurrence, but to woman, I'd imagine it would be a very concerning experience... especially if she decides to go with boxers instead of briefs.

Also, differences in body strength will not really be all that apparent for most of what she does unless she tries pushing herself beyond normal daily activities. 99% of the day is spent doing things that any woman would be able to do without really trying that hard anyway. There would just be that occasional moment for a while where she realizes she can open that stumborn pickle jar... these would be novel experiences for her but not really require much of an adjustment period.

Eating and talking would be different, but not require a significant adjustment period. The transition from gender nonspecific to male specific vocal structures is a pretty spontaneous change that happens in adolescent boys. Despite this, most boys do not even notice it has happened until someone else points it out to them; so, I would not imagine this being an issue to physically adjust to, it would just be a bit different.

  • $\begingroup$ Thank you so much for putting a lot of thought into it and especially the points about men walking habits. This is, indeed, something that people rarely talk about. $\endgroup$
    – Otkin
    May 1 at 0:34
  • $\begingroup$ Good answer, interesting. As dongles are involved, hey where famous sitting posture, also laying and(or) sleeping one as well(basicaĺly the same stuff to avoid pressure, which not necessarly leads to noticing it immediatly, most irritating part about it actually, but may have consequences) $\endgroup$
    – MolbOrg
    Jun 17 at 15:41
  • 1
    $\begingroup$ @MolbOrg Ah yes, the good old sitting with your legs spread. I imagine she will hurt herself a few times trying to sit down too quickly before she learns... and if she has a good sense of humor about it she will exclaim "... and I oop" every time. $\endgroup$
    – Nosajimiki
    Jun 17 at 16:42

You might be best to study the experience of woman who Have transitioned to trans men. Your story is Not identical to thier but there is similarities . Basically she will have to deal with a sudden increase in strength, Bone density and size. Many of these changes occur in woman transitioning.

Something to consider: Is her new body attracted to men? A lot of attraction is Psychological but certainly not all of it Physiology also plays any important part.

  • $\begingroup$ The key point here is that changing the body will change the "mind" indirectly. For example the new body will produce different levels of testosterone/estrogen/cortisol/adrenaline and the hundreds of other hormones that regulate mood on a day-to-day basis. $\endgroup$
    – Daron
    Apr 29 at 22:20
  • 3
    $\begingroup$ I was considering this, but I ultimately came to a conclusion that the experiences of transgender individuals who transitioned are not applicable. Two main reasons are: 1) Even after the full transition the body is still the original body; 2) the transition is a gradual process while in my case the change is immediate. There is no adjustment period, no preparation, no expectations. I am also not sure if transitioned XX body is sufficiently close to the native XY body. I am not a specialist in this topic, so my words might not be clear enough. Feel free to ask for clarifications. $\endgroup$
    – Otkin
    Apr 29 at 23:36
  • $\begingroup$ @Otkin The experience will be similar in some ways and different in others. $\endgroup$
    – Daron
    Apr 30 at 1:04
  • 2
    $\begingroup$ Trans men do not actually gain/loose all of their female inner workings. While hormone therapy can cause some changes in an adult, many aspects of the human body can only form during specific developmental phases of your life. $\endgroup$
    – Nosajimiki
    Apr 30 at 13:36

Necessary disclaimer that I'm not an expert and the following speculations are based off of personal research.

Like any old soul in a new body, she would have to adjust herself to the physique. She'd likely be taller than before, and with longer limbs, which really won't cause more than the occasional clumsiness unless the difference is drastic. If she has the same muscle mass as before, her body may feel slightly heavier to move and use. If she has proportionately the same amount of muscle mass, she'll have to get used to being a little stronger, which means for a bit she may grip things too hard or push things too far, etc. So from a physical perspective, all the normal side effects that come with having a new body and getting used to that, and being clumsy while you still figure it out.

On a more chemistry side of things, she's going to have more testosterone, which comes with effects like a higher sex drive, increased bone strength, higher metabolism, and gaining muscle mass more easily. She'll have less estrogen, which means less serotonin (the happy stuff) and more mood swings. Mens bodies also collect visceral fat (unhealthy fat) more than subcutaneous fat (good fat), which means they're more prone to health conditions like diabetes and heart disease, and their blood sugar levels change less easily than womens. How does all of this make her feel? She may have more energy day to day, but her mental health will be more fragile and moody. She might be surprised at how quickly she loses weight and gains muscle (if she exercises), and of course, the higher sex drive.

Psychologically, (the biological effects on the brain, since you said not to mention the mental effects), I'm not sure if there are really any differences in the way a man and a women think. To my knowledge, this area is still inconclusive. Some say women are instinctively more social and "motherly", however research suggests this is likely societal conditioning rather than biology.

A few more notes on the behavioral aspect of things, she'll likely be acutely aware of her new reproductive system for a while, as she'll be used to her old physique. The lack of weight on her chest and the new weight on her hips may feel uncomfortable. In my personal experience as well, women tend to hold their backs slightly arched compared to men, and stand with their feet closer together. She may continue to adopt these tendencies in her new body. Also, if her body was pretty curvy before, she'll be unused to the new, straighter body shape, which'll be especially apparent when she puts on/takes off clothes.

  • 2
    $\begingroup$ "She'll likely be acutely aware of her new reproductive system for a while" +100 😃. ("New"? "For a while"? Seriously, how many guys aren't "acutely aware" of their "reproductive system" more often than not?) $\endgroup$
    – Matthew
    Apr 30 at 0:23
  • $\begingroup$ I wouldn't know, I'm a woman ahaha. But I know if I had a new reproductive system it would weird me out for a looong time. I don't know if I would ever get used to it, or get over having a flat chest 😩 $\endgroup$ Apr 30 at 0:27
  • $\begingroup$ If it lasts for more than 3 months, then she is "chronically" aware of her new reproductive system. $\endgroup$
    – Nosajimiki
    Apr 30 at 15:27
  • $\begingroup$ @Matthew I am with cassidia.68 on this. I am also a woman and I would probably have an even more exaggerated reaction to a sudden appearance of something unexpected between my legs. $\endgroup$
    – Otkin
    May 1 at 0:28
  • $\begingroup$ @Otkin, well, sure 🙂. I didn't mean the character wouldn't have a reaction, perhaps stronger initially, it was more the implication that this reaction would go away over time I, ah, disagree with. The "OMG!!!?!" factor may fade, but awareness — yes, sometimes "acute" — won't fully go away. (Not if the body isn't impotent, at least.) $\endgroup$
    – Matthew
    May 1 at 14:00

Not the answer you're looking for? Browse other questions tagged or ask your own question.