Here’s a little data.  I have a 1961 sewing book with sizing charts for various categories (girls, teens, juniors, misses, women).    The absolute largest fattest size in the junior chart is size 17, with measurements of 37-28.5-39. To compare, according to a study from 2016 (http://ojs.cnr.ncsu.edu/index.php/JTATM/article/download/9857/4934)) the average junior (age 18 to 25) today is 38-32-41.  Insane!