I's interesting to see how much obesity levels have increased in the last 30 years. I don't think it's because people have made a conscious choice to be overweight, but I think it's harder and harder for people to avoid it, because society is set up in a way that makes us lazier and encourages us to consume more.
For example, many more jobs are now desk-based rather than physically active, more of us drive, so don't walk to work/shops/bus stop/railway station, we shop more online so don't go out to shops, tvs all have remote controls so we don't have to get up off the sofa, ready meals mean we don't spend time slaving over a stove, and most information is available at the click of a mouse/swipe of a screen so we don't need to go anywhere to find it. Ds and I were talking the other day and he mentioned those Alexa things. "Ah yes," I said, "Something else to make us all lazier".
Food is generally quite cheaply available, and the cheapest and most intensively marketed stuff is the high carb crap. There's also quite a culture of snacking and "treating yourself" these days, to the extent that if you refuse a carby treat being offered round, you are seen as being a bit joyless or holier-than-thou (at least, that has been my experience). It's actually quite hard to eat well and move a lot, unless you make a conscious decision to do it.