I have a big gut, and no ass, but I don't ever have this problem... I use a thick, wide belt and it holds up my pants fine.
Maybe it's a question of belly fat density. My gut is pretty solid.

Not at all your height, size, or even gender, but I'll just say you can use mybodygallery.com.
Pick your basic body shape and height, then increase the weight.

The rolls under my arm getting thick enough that my arms rest at a wider angle. And then those rolls joining on my back. And then those rolls growing another roll beneath them...

I typically have to make that call myself. But, I was stopped from sitting in one of those flimsy metal lawn chairs once. Not only was I too heavy, but probably too wide. I would've gotten stuck.

I know I've said it on here before, but I managed to warp an army bed. I actually did damage to every bed I had in college through sheer weight.

I also get these Fiji visits. Almost half of my notifs are Fijis visiting my profile.

For me, I would guess somewhere in the 500s is where I'd have to be sitting most of the time. 600s for not doing housework, even occasionally. So I'd say somewhere in there.

I had manboobs really bad when I was younger, enough to actually be tight in shirts along with my belly. But as I've gotten a bit older and having to lift heavy stuff, they've shrunk. Of course, my belly also grew a lot more, so maybe not...

Okay then.
Seeing as the initial post is now gone, have you ever broken a bed frame?
I for one managed to severely bend an old iron bed in college, and very nearly broke two steel tube ones in college.
These days I use a mattress on a foundation on the floor, but even that has a snapped board...

I'm fairly certain I've said this before, but if you're tall, 7 almost comes with 6. Cars, booths, and clothes don't fit if you're 6'3" and have a hard time bending over.
That being said, even with some weight lost, 7.