I haven't really tried with vegetables (not interested taste-wise), so it might be the carbs / fruit sugars that weren't great for my gut biome, which I suspect is messed up as it is for many people nowadays.
However, I’ve identified many people that were vegans just by their looks before they (inevitably) announced it. You’re supposed to be able to supplement your way in to what you need but either the majority don’t or they’re still missing something.
There's no need for belief, all over the world vegetarians live around a decade longer. There could be any number of confounding factors of course but the burden of proof concerning health and diet is definitely on the pseudo-carnivores consuming their packaged flesh.
Controlling for wealth, total calories consumed, and a number of other known and suspected positive and negative contributors to longevity, quantity of meat eaten seems to end up positively correlated with longevity across the board.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8881926/#!po=26...
The better conclusion might be that vegetarian is an elite affectation that is not as bad for you as the competing elite affectation of overeating.
I won't speculate on whether this would apply to everybody but my hypothesis is my health issues stemmed from gut biome disregulation caused by - way too many causes to list - and somehow only total elimination of carbohydrates and plant matter fixes it.