I travel a lot and find it hard to maintain the same exact diet even though I cook 95% of my meals at home. Even just between US cities, there are different fo

I travel a lot and find it hard to maintain the same exact diet even though I cook 95% of my meals at home. Even just between US cities, there are different foods at the grocery store at different price points that would make it unreasonable to stick to an identical diet, so it's hard for me to believe that everyone in these anecdotes has identical intercontinental diets. Yet these anecdotes are never about obvious differences that could explain large calories swings. They always focus on cocksure yet vague claims about chemicals and additives. It reminds me of people claiming that switching from corn syrup to cane sugar Coca-Cola, a magical elixir, when they traveled to Mexico must obviously be the responsible for some bodily change they allegedly experienced with no further interest in any competing explanation.