Newsflash: eating food that people have eaten for thousands of years and thrived on, is better than eating highly processed, deep-fried, and/or chemical additives-rich junk that incidentally makes money for their manufacturers and sellers.
Eat more food grown on plants and less food manufactured in plants.
(To be sure, a smallish component of meat and dairy is often advised, but if your diet consists of only this (and perhaps bread or your locale's starchy staple) then health problems shouldn't even be surprising.)
Why do people believe that food consists only of Carbs, Protein and Fat? Perhaps with a sprinkling of vitamins and minerals, which can just as easily be gotten from supplements? There's stuff like probiotics, enzymes, and elusive co-factors and who knows what else that science has not yet even discovered, let alone understood and described.