Personally, I think the biggest factor is a primarily sedentary lifestyle, which could be the exacerbating factor that multiplies the negative effects of sugar

Personally, I think the biggest factor is a primarily sedentary lifestyle, which could be the exacerbating factor that multiplies the negative effects of sugar and saturated fats intake. We're spending more collective time as a society sitting on our butts than ever before, so many people drive everywhere instead of walking or riding a bike. We can get everything delivered to our homes instead of having to go to a store, walk around and pick it out ourselves. So much more happens purely online now, even something as simple as going to the corner store to rent a movie is a thing of the past. All of these things used to add up to at least some physical exercise. Perhaps not ideal amounts, but it got people moving at least. Obviously this is not universal, a lot of people still do get their movement and fresh air, but my thinking is that it's less than ever before, combined with access to high-calorie food that is also easier than ever before. So in that sense, physical activity, or the lack of it, is the force multiplier in regards to one's diet. I try to get at least 30 minutes of some sort of activity in every day, and preferably more. Just a walk outside or cleaning the apartment or doing a project. Most days I walk to the stores to shop, as a conscious choice to get my physical activity covered.