If you attribute our healthcare outcomes exclusively or almost exclusively to "lifestyle choices," then you're talking about the nature of our character.
What you're saying is that the US has worse healthcare outcomes because Americans are of lesser character than the people of literally every other developed nation on earth. And, I mean.....that may be true, I wish I could argue against that conclusion. But it's a silly conclusion nonetheless.
It's a complex system, with complex factors. And yes.....lack of education, availability/cost of mental health care, availability/cost of overall health care, poorly designed supplemental food programs/aid, massive wealth inequality and significant poverty, a system that subsidizes and floods the market with terrible food choices, etc. etc., are pretty important f'n factors. Compare those systems with our peer nations, and we look really shitty.
The reasons that we have shitty health outcomes at a massively higher price are a lot bigger than "Americans are bad." And that's a lazy, irresponsible answer anyway. Because it absolves all of us of any responsibility -- American person X is unhealthy? Well, that person makes bad choices, fuck them. It absolves me of any role as a member of a society that has designed a system that is incredibly effective at delivering bad food options and the like, and incredibly ineffective at delivering basic physical and mental healthcare. I can and should demand better of the system that I am a voting member of.
Naaah, let's just shovel all the blame on poor people living in food deserts and shit, and skip down the road, blissfully obligated to do NOTHING to improve our systems. THAT is the American way!