Most of human behavior is irrational. If we were all perfectly rational, we would have healthy diet and exercise habits from the get go, and we'd have plenty of time to prepare food and exercise, because we wouldn't waste any time on entertainment.
Isn't this almost true by definition? If it actually works, it's not a "fad", just "science" or whatever. Advice like "eat more vegetables" and "don't drink alcohol" probably do work, but they're ingrained enough that nobody thinks they're "fads".
Besides, the breakfast cereal movement it created quickly devolved from the Kellogg's and Post's original healthy cereals, Corn Flakes and Grape Nuts respectively, into the sugar-laden craze of 1950's cereals. Even Graham crackers were healthy and bland at the time, but we now associate them with cinnamon and sugar.
Until then, I'll keep eating foods consisting of proven healthy ingredients, even if they are classified as Nova 4 ultra-processed, such as lasagna made using my great grandmother's recipe or ancient Mayan dishes like pavo con achiote and also cochinita pibil, while avoiding foods that are proven unhealthy despite the not-ultra-processed Nova 3 and lower status, like Cronuts, potato chips, and bacon cheeseburgers.
Achiote seeds add a bright red to yellow color, depending on the concentration, and add a mild earthy flavor. This puts it in the Nova 4 ultra-processed foods category, ostensibly because the color can make food more attractive. This is as opposed saffron stigmas, used in some traditional European dishes, which add a bright red to yellow color, depending on the concentration, and add a mild earthy flavor. Why adding achiote makes something ultraprocessed and adding saffron doesn't isn't explained, but I wonder if there's a predilection toward traditional European foods.
The Nova classification only counts fresh fruits and vegetables as unprocessed, which is Nova 1, so almost all foods are processed foods, Nova 3, or processed ingredients, Nova 2.
I eat healthy food and avoid unhealthy food, but the Nova classification system is so poorly done that it is meaningless. Even going off of actual levels of processing, instead of the ingredients, doesn't help much. One of the earliest processed foods, hominy, is much healthier than the unprocessed counterpart, and when Italians relied on polenta made from unprocessed corn, they became malnourished and suffered from pellagra, while those in America relying on the otherwise identical grits, made from hominy, weren't malnourished.
That's why I go off of actual research proving which ingredients are healthy based on the effects of adding them to or removing them from a diet that otherwise stays consistent in volume and calories, instead of the vibes-based categories the Nova classifications use, and the vague research showing that rich healthy people who exercise eat some things and poor unhealthy people who don't exercise eat other things, but never showing that eating some things actually makes you more healthy and eating other things actually makes you less healthy.
If similar levels of research into ultra-processed foods were applied to other statistics, they'd find that ice cream sales lead to drowning and owning a Ferrari makes you rich.