How to interpret「～そうになるのを、」


I am having a hard time understanding the grammar of the following sentence.

> 贅肉がはみ出して落っこちそうになるのを、体に巻きつけてあるみたいな感じだ。

In isolation, the two parts make sense.

> 贅肉がはみ出して落っこちそうになる  
>  [Her] excess fat stuck out, as if it were about to fall off.

> ...を体に巻きつけてあるみたいな感じだ  
>  It was as though ... was wound around [her] body

But when combined with this のを、I cannot understand. の appears to nominalize
なる, but this is part of そうになる which I am stumped with.

How should i interpret this? Thank you :^)

Edit: I've added the whole text, to provide better context. This is a
description of Matilda's mother. Perhaps my incessant questions about Matilda
will help someone else reading this book in the future :)

>
> 大柄な女で、髪はプラチナブロンド（薄い銀白色）に染めている。ただ、生えぎわのあたりにだけ、ネズミ色がかった茶色の髪が見えかくれしている。こってりとお化粧をしているが、気の毒なくらいにぶくぶくだ。**贅肉がはみ出して落っこちそうになるのを、体に巻きつけてあるみたいな感じだ。




For the form of the relative clause, see [internally-headed relative
clauses](https://japanese.stackexchange.com/questions/68317/head-internal-
relative-clauses).

V～そう, as you probably know, means 'looks like [it will] V', 雨が降りそうだ, etc. This
form is a な-adjective, and thus all the conversions that apply to those can be
made:

問題になりそうなもの

and as in the example sentence, it can be turned into an adverbial phrase,
with なる adding the sense of 'coming near to [looking like it will V]', e.g.,

焼け落ちそうになる, 'come near to burning down'.

Your translation 'as if about to fall off' quite captures the sense. なる seems
not to offer much extra in terms of sense, so that there is only a subtle
difference between

落っこちそうになるのを

and

落っこちそうなのを




For the form of the relative clause, see [internally-headed relative
clauses](https://japanese.stackexchange.com/questions/68317/head-internal-
relative-clauses).

V～そう, as you probably know, means 'looks like [it will] V', 雨が降りそうだ, etc. This
form is a な-adjective, and thus all the conversions that apply to those can be
made:

問題になりそうなもの

and as in the example sentence, it can be turned into an adverbial phrase,
with なる adding the sense of 'coming near to [looking like it will V]', e.g.,

焼け落ちそうになる, 'come near to burning down'.

Your translation 'as if about to fall off' quite captures the sense. なる seems
not to offer much extra in terms of sense, so that there is only a subtle
difference between

落っこちそうになるのを

and

落っこちそうなのを

