So clearly it’s something to do with the difference in their lives in the USA, but your first response is to treat the symptom with drugs rather than look at their life holistically?
Just off the top of my head the food (portions, quality, etc) in the USA combined with how much people no longer can walk vs being required to drive are a huge contributor to weight gain of immigrants to the USA.
Sure, much easier to make a decision for yourself that helps you cope with the USA lifestyle than it is to change the USA on a short time scale.
There are of course other decisions that might help cope, like moving to one of the few walkable cities we have or structuring your life to reduce the lifestyle, but those all have a lot of other effects like completely upending your current life.
A person can take a shot every week.
What’s a person supposed to do about a problem that’s probably tangled up in several major areas and would require large reforms across the economy? We can’t even get mandatory minimum paid leave or healthcare for everyone (both of which might well be components of fixing it “right” anyway!)
This is likely a problem that spans our food culture, business culture, economic structure, built geography, and social benefits system, among other things.
You can spend a lifetime fighting those and be fat the whole time because despite massive effort and objectively incredible achievements you and your movement only got us 5% (that’s a lot!) down the road towards fixing these things, in fifty years.
Or you can take a weekly shot and be well on your way in a month.
Working on the “real” fix is definitely something we should do (it’s not like the causes of this aren’t causing other things to suck, too) but even people doing that would probably like something available that they, not just their great-grandchildren, can have.