I think the lifestyle part depends a lot on where in the US OP would end up. Places like Boston and NYC are not car-dependent at all and most people you will meet are a normal weight and have a decent diet. There is also a ton of cultural diversity within NYC and lots of amazing food (especially if you have disposable income). Boston has many students and postdocs coming from all over, so in an academic circle you will easily have a young diverse friend group. It's definitely a different lifestyle than living in some other parts of the US, which probably are more of a negative compared to EU - though if you're into nature there are some really beautiful sights in parts of the US that make for relatively cheap vacations. There's also something to be said for the US college experience, like I wouldn't want to live in a smaller college town as an adult but some of them are super fun while you're an undergrad.