Having lived in Southern Europe and no being in the USA, one major difference is the amount of walking you do in the Old Continent.
It is a great complement to the food diet.

The USA were build for wheels, with roads and parking spots evertwhere (besides NYC and other exceptions). Europe has 3,000 years of history which makes it an aweful place for cars (have you ever driven in Rome or Paris ? Good luck...)
You have to park further or simply walk all the time. Some older buildings even do not have elevators.

I was in Portugal 3 weeks ago and I was burning TWICE the amount of calories vs. here in California. (according to my apple watch)

Eat good, and walk.