There is a strong correlation between highly processed food intake and metabolic diseases.

1960s and 1970s Americans drove a lot, cars were a symbol of American culture. But they were a lot slimmer and healthier than today. Look at any video from NY or LA streets from that time. These guys and gals were normal office workers, not hunters and gatherers. But they looked completely different.

Perhaps not incidentally, their diet was completely different, too.

Isn't this a popular saying among health/fitness people: "You can't outrun a bad diet"? That would seem to prioritize reorganization of food/diet over any limitation of cars.

The cause is too much food/the quality of the food people eat.

Exercise plays a small role in weight loss / management, but people should still do it for the other benefits.