In the book, "The Check List", by Manny Alvarez, M.D., there's a long list of body changes we go through as we age. I won't list all of them, just the main ones I think pertain to healthy food consumption.
The list assumes 100% function for the average 30 year old and gives the remaining percentage of function for the average 75 year-old man.
*Brain weight: 56%
* Blood supply to the brain: 80%
*Number of taste buds: 36%
The last one is most important, in my opinion. I think it explains why so many people gravitate to higher calorie, less nourishing foods as they get older. It may also explain why so many diets fail (80%?).
I believe there was a recent thread on, "What's the best pizza". Just look at how many replies there were compared to the average. Pizza is definitely very tasty and fits the bill for taste buds in decline. Although I did the opposite: I occasionally ate pizza when I was young but stopped completely 11 years ago; I also ate such tasty items as bacon and eggs but haven't done so since I became a vegan 11 years ago. I don't eat processed foods (with the exception of 3 or 4 that are minimally processed) and I like the taste of regular whole foods without dressings or seasonings. So I guess I'm lucky because I don't feel as though I've lost any of my taste buds.
But if Dr. Manny is correct, it kind of explains why so many people are addicted to high calorie processed foods. It tastes normal to those who are in the process of losing their taste buds. And nothing anyone can say will save them from themselves. Haven't you heard people say that healthy food tastes like cardboard? Now you know why. (Of course other factors may play a role.)