I am far from a cyclist...but in summer season I like to ride my gravel bike sometimes up to 2 -4 hours. What happens there is enough of getting a glimpse of what an be out run, out cycled. And no, fat people can't cycle forever, cause it is 'efficient'.
Sure, for general population which is pretty sedentary (even if you train regularly) it is a good call to have an eye on 'junk food'. But there was - and still are preople out there, who work there a... of physically: they seem to be lean and mean and often these kind of people don't fret about macros ad micros. In it's most simple and basic way, food has to make you full. If you can not afford 'high quality food' or just don't have access to it you simply eat, whats on the table or in your hands.