Comment by greeneggs

I'm not sure it is a science problem, i.e., processing food makes it unhealthy. I think it is more an economics problem; food processors don't have the incentives to care about the long-term health of the food consumers.

Food processors have incentives to improve their logistics (e.g., increase shelf life) and to make the food taste better (or even, hopefully, addictive). Some brands try to make their products appear to be healthy, but consumers generally have little information about what is going into processed food, so appearance might not mean much.

Of course, even unprocessed food like fruits and vegetables has been heavily engineered by breeding, especially in the last century---and again, not to make it healthier.