fact of the matter is, there is no one diet that will perfectly suit every different kind of person on this planet. we have all been evolving separately at different corners of the world, for a very long time now. the diet and way of life fitting to an Inuit, would not be fitting to a Khmer, and visa versa. while some people in this world do very well on chronically very low carb diets, some do not. in fact some populations seem to live well on much higher chronic carb consumption. and still many more people are somewhere in between
it really just depends on your ancestry, and in the western world anyways where the lot of us can go to the supermarket and pick up an global variety of foods (for better or for worse), your own self experimentation on what you can and cannot handle for starters, and eventually what you thrive on over the long run. humans are quite adaptable, there is no doubt that regional adaptation to diet has occurred just like it has with race and everything else genetic. for that matter we wouldn't be the only mammalian species to show such adaptations to diet, i mean look at the polar bear compared to the brown bear: polar bear eats a primarily carnivorous chronic VLC diet, while the brown bear eats a diet primarily consisting of fruits supplemented by whatever else it can find. both of these bear subspecies ("subspecies" being analogous to "race") can produce fertile offspring together, so they are the same species (just regionally adapted "races" of the same species if you will), but they both have rather healthily adapted to rather differing diets. wolves are much the same, showing regional adaptations ie subspecies, each eating the food they can hunt of find in their respective parts of the world. which is usually any animal they can take down, but as anybody that is familiar with canids will tell you, they are nothing if not opportunists
if i recall there was even an experiment once transplanting a carnivorous lizard, to an isolated island, and in just a few generations the lizard was already showing intestinal adaptations to a primarily herbivorous diet (i'l see if i can find the study). granted the transition was likely not smooth at first...but the point is, is that an hardy creature will adapt to any new environment and its dietary challenges it finds itself in, and if it can't it either A) dies out, or B) returns to whence it came (the option us humans likely face with large scale SAD diet if i may say, given there is a ratio between "positive adaptations to any new food source" and "the negative side effects of any new food source", and when it comes to the modern processed diets, humans are on the loosing end of that relationship). and the fact of the matter is over the many thousands (if not millions of years given some other theories) of years, various human populations at various corners of the world and everywhere in between, have been adapting to their environments and everything that comes with it
what does this mean? does this mean not to eat avocados if you are not from the americas? or any other given set of food/region of origin scenario? well, in the world we live in today its a bit more complicated than that. and when it comes to instincto and "what you are craving", well if you were living in your native part of the world you would instinctively crave only your native foods. you can see, how it would be a bit more complicated in todays world...
to put it simply, you just have to keep your ancestry in mind to give yourself a starting point, and then just experiment from there. and don't be afraid to ask questions and share your experiences, either here or with your family
