That'd be a BMI of 47. There isn't a lot of statistical data for such high BMIs, but [1] lists prevalence of BMI>40. In Germany 1.2% of men and 2.8% of women had a BMI over 40 in 2011, in the US it was 5.6% and 9.7% respectively in 2016. That's nearly four times as many as in Germany.
It’s the suburban mom (or dad sometimes) who wants help losing a little weight. Instead of being 300lbs like your example, she’s 160lbs and wants to be 140lbs.
I do want to get back into biking though. Haven’t ridden in a long time.
How does that compare to, say, Japan? Why is Germany so much fatter?
Most of the industrialized west is following very similar growth curves here to the US. America just got their first. Even Asia isn't immune - Korea has been following similar trends, as have parts of southeast asia, etc.
I suspect the prevalence of GLP-1 class drugs will halt this trend before the rest of the world catches up, but without them or similar drugs, I would have bet that 50 years form now much of the rest of the world would look just like America
Those that still want to reduce their weight: All of them are on GLP-1s now (and losing weight!)
Those that had totally given up: They had long since stopped attempting anything to reduce their weight
I suspect that the larger you are, the more likely you are to fall into that second category - getting to 300+ lb involves a certain level of accepting defeat to begin with.