Actually the one-size fits all seems to be quite good as there don't appear to be any porkers there.
Now if it were RAF aircrew or RN submariners I bet some slack would be taken up
I recall many years ago, when we had pride in appearance, that it was the norm to have one's V-force zuit suit remodled and lined to improve its fit and style. What is to stop the user having a bit of nip and tuck?