This is probably not a great forum to take nutritional advice from - LW many have human rationality down better than most but the domains of food and methods of thinking are far apart.

Questions about what the most instrumentally rational practice is for a task shared by all humans are not not outside the domain of human rationality. If it happens that lesswrong is as bad at nutrition as you imply then that represents a failure according to the expressed and actual values of the site.