[esotericn]

I think it's really difficult to quantify sub-optimal in this context because it requires the identification of like, actual serious benefits or bad effects, as you say re defining 'malnourishment'.

If you could show that, for example, on average a meat eater had a higher IQ than a vegan (or vice versa), or is stronger or something, and you somehow exclude the confounding effects (e.g. vegans in the West are generally wealthier and more educated than the average) that'd be a solid example.

A lot of the time it seems to come down to things like short-term digestive effects or specific deficiencies.

The car example is interesting. I wrote a reply about this earlier actually. I recently went from a 1998 banger to a 2019 shiny fancy thing. They pretty much do exactly the same thing. The 1998 car was theoretically less reliable but in practice it never skipped a beat.

I mean, it's less shiny, makes more noise, pollutes more. But 'sub-optimal' - I mean it really depends on your metric. In terms of going places it was the same.