content: There is a treatment called hormone replacement therapy. Hormone replacement therapy works by giving a natally male patient female levels of sex hormones, or a natally female patient male levels of sex hormones. This causes the initiation of a second puberty in a patient in which they develop most of the biological traits of the opposite sex. One biological trait a patient would gain is what's known as the secondary sex characteristics of the opposite sex, which is the sexed outward appearance a man or woman has. These are some examples of thousands results you could find online:  1 2. Someone with a masculine body transitioning to a female body would gain female breasts: 3 [4] (https://en.wikipedia.org/wiki/Hormone_replacement_therapy_%28male-to-female%29#Breast_development). Gender dypshoric patients going from a feminine body to a masculine body would gain an increase in muscle mass 5 4 and MtFs would gain a smaller muscle mass, like a women has to look feminine 4. MtFs would get a reduction in body hair like women have 3 and FtMs would get an increase in body hair like men do 6 4. MtFs develop emotional fluctuations from fluctuating estrogen, especially during their puberty, like a woman gets during a period. Both FtMs and MtFs develop brain regions that are similar to the opposite sex: 7. There are many, many changes hormone therapy provides. This therapy is so powerful there are athletes who were born female, became male, and then successfully competed against men in professional sports. Scientifically, someone whose gone through this process is intermediate between male and female. However in a practical sense calling someone female when they are literally  mostly male is just stupid.  Neurologically the most important part of the brain in regards to sex, the part responsible for inflicting suicidal feelings for undesired gendered behavior, is of the opposite sex.