A realistic weight is whatever you weigh when you're eating normally and keeping active. IMO, of course.

A weight that you can maintain without bulemia, for a start, I would think.

125 pounds = 8.93 stone

I personally would consider any adult 5' or over who weighed 125 lbs to be on the smallish side. I wouldn't hold an opinion that they were underweight or malnourished without further information.

According to US guidelines based on BMI, an adult 5'6" tall who weighs less than 115 lbs (8.2 stone) is underweight and one who weighs more than 155 (11 stone) is overweight. A lot of us fat activists think the range of "normal weights" is much too narrow and represents only the low end of a weight range in which it's possible to be healthy.

Most people don't read primary sources. Which probably isn't a good thing. Most media don't relay the information from primary sources accurately. Which probably isn't a good thing. And round and round we go, and what am I doing in this handbasket?

I read The New Yorker (my mother's copy) for decades, and in the past one would expect The New Yorker to do a pretty detailed investigation that would include such information. These days, though, I don't know.