Anon dates a girl

Bruh you skippin leg day then. Legs can easily be half your body mass. The center of mass for an average human is their naval, which is only a few inches from their waist. If she did track or worked out then she could easily have half her mass in her legs.

It is POSSIBLE for instance: for a trained athlete with a focus on one part and ignoring compounds etc. that effect other parts largely to have VERY disproportionate any muscle group. However- on average a persons trunk is 48-51% of their body mass. The average woman is 51% trunk by mass. Most human beings you will meet will not have 50% or more of their mass or weight located in their legs. Your head and neck average 7-10%. Arms tend to also be in the 10% range. It is POSSIBLE but not common for a humans mass to be 50% or more in their legs.

Even if you do not skip leg day- it is also not generally easy for your legs to be half your body mass. It takes quite a bit of work and without drugs or PES- likely years. And to the original larger point- regardless of what percent of her mass her legs were- as she exists now she is a whole and complete person, and thus would still not constitute a “half” of anything except perhaps “half” the mass or weight she was with legs.