The problem with the Western diet is not one of deficiency, but one of excess. We get too much of a good thing – too many calories, too much of the wrong kind of fat, and too much salt. As a result obesity, diabetes, and hypertension are growing health problems.
There also does not appear to be an easy solution – voluntary diets founded primarily on will power are notoriously ineffective in the long term. Add to that is the marketplace of misinformation that makes it challenging for the average person to even know where to apply their (largely ineffective) will power.
It can be argued that this is partly a failure, or an unintended consequence, of market forces. Food products that provide cheap calories and are tasty (sweet, fatty, or salty) sell well and provide market incentives to sell such products. Consumers then get spoiled by the cheap abundance of tempting foods, even to the point that our perspective on appropriate portion sizes have been super-sized.