It probably is gradually done, but I recommend looking at the amount of sugar each brand of bread has next time you're at a supermarket. Or milk, lemonade. Or other common groceries. It really is crazy to see just how much of -everything- has added sugar. Including products that are branded as "healthy". AFAIK Naked juice is a great example of this.
As a remote worker with a great schedule, I have the time to do such research. But not everyone is in that situation, particularly if they have a job and have kids, etc. Brands can essentially lie through their teeth and get away with labeling as the regulation can be quite loose.
Many people "know" processed food isn't healthy, but to what extent it's bad for them, maybe not. And it comes down to time and cost. Also, some people don't really grow up knowing what "healthy" food is like.
> It's from bad diet over a long period of time.
It doesn't help that healthy foods are more expensive than food that's absolutely terrible for you.
I think Mexico's new laws around food labeling is the way to go, but time will tell if that's actually effective or not.