[tracker1]

Take any 10 people and give them trace amounts of X (whatever X is) over the course of 5 years... they won't respond the same. Some will go through it easier than other. Some may have allergic response, others won't.

As for the general advice to avoid sugars, grains and seed oils. These are all things whose consumption correlates the most to increases in heart attacks, obesity, dementia and many related diseases. They are absolutely not required for anyone and for most of the population consumed in quantities that cannot be justified as healthy or safe.

Eating lots more vegetables (in scale and variety) and some more fruits (keeping sugar manageable) generally corresponds to better health. Regardless of other macro nutrition (though I feel that meat, eggs and fish are fine). "OPTIMAL" historically speaking has mostly come down to cost and availability. Optimal for man, in general comes down to what could be raised, gathered, hunted or foraged relatively locally. That would include regular periods without food, and a few in excess.