Oh, dear, Gabriella, you were really asking for trouble there!
It's just not done nowadays to suggest that anyone's obesity can possibly be their own fault - they must have 'issues' (medical or not).
However I dare say many of us will know someone who has no 'issues' except that they are extremely fond of their food. A relative of dh has been extremely overweight for years but he never minded admitting that it was because he thoroughly enjoyed eating - as anyone who had a meal with him could see from the heaped-up plates of food.
Nowadays I think it's more a case of a great deal of wine, not that any of this has stopped him being outstandingly successful in his career.
On our first visit to the US in the mid 70s I was astonished to see so many hugely obese people - relatively rare in the UK then - but it was quickly obvious that the easy availability of cheap, fatty fast food everywhere was a prime reason. I still remember, on our first morning in a 24 hour breakfast place, seeing an extremely fat boy of maybe 12 tucking into an enormous breakfast, just one part of which was a pile of pancakes several inches high, with a huge lump of butter on top.
I'm sure so much of it is down to cheap, fatty fast food, though what anyone can do about that I don't know.
On a visit to Prague quite a while ago an American tourist asked me how on earth it was that the people were so slim, when menus just about everywhere were very heavy on fried potatoes and dumplings, hardly any veg or salad.
Answer (presumably) because there was virtually no fast food, people cooked from scratch, and few had cars, so there was a lot of walking.