Counterpoint: I've been Keto, also advised by a doctor, and have eaten basically nothing but free-farmed meat and cheese, along with lots of veggies, and my overall health has gone from "OK" to roughly "great." (labwork, etc.)

I've since transitioned to low-carb rather than proper keto, but the increase in keto foods (things made with healthy fats, allulose rather than table sugar, etc.) has made it much easier to do proper keto.

As parent said: YMMV, and we all have different bodies, needs, etc.

Corollary - I did keto for just over a year while on a vegetarian diet with the main goal being weight loss. During that time I felt extremely energised and healthier. While not strictly vegan, my diet was basically the low-carb nuts, legumes, mushrooms, fruits, vegetables, eggs and cheeses. I did have to add a few supplements, otherwise I'd feel like utter shit, magnesium and electrolytes mainly had a significant effect on my mood. But otherwise it's the healthiest and most alert I've felt since I was a teenager.

People I mention this to assume the toughest challenge is variety but as I love to cook it wasn't too hard to make it interesting each day. The toughest challenge was convenience, you grab a coffee or a lunch with friends and there's very few places that cater for all. The second most challenging aspect was cooking meals for the family, as I am the main cook for my wife and kids who did not at all buy into a vegetarian diet let alone keto, but that again wasn't too bad since I could just cook a normal meal, scrape out the bits I can have and whip something up for me afterwards.

After about a year on that diet I ran a sub-1hr 12km charity race which isn't exactly a world record, but not bad for a 40-something always-recovering alcoholic with weight and mental health problems. I'd definitely recommend keto (with proper medical supervision) but... maybe not at the same time as trying to eat less meat.

> I generalize that for many people less meat and meat products may lead to positive health outcomes, but I am no scientist.

And you fail to take into account the healthy user bias. Plenty of people become vegan because it's advertised as healthier, which means it filters people that don't want to be healthy more than some other diets. Also, vegans are very aware that they diet may lack X or Y so they pay more attention to nutrition. For example, lack of B12 was a meme against vegans at some point, which means now most of them are aware of B12. I can't say the same for the rest of the population.

When it comes to the "healthy bias", i just do what healthy people do as long as it's kinda supported by science. Even if we don't have the evidence yet it's still worth looking to see which was the science is poining

> We truly are what we eat.

Well, I’m not trying to be a vegetable.