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.