TIL: The 2000 calories per day recommendation you see on food labels that say things like “Eating this biscuit uses up 20% of your recommended daily calorie intake” is not really based on a ton of rigorous science.
Rather, it seems to be a very rounded version of a wide-ranging number of calories that Americans reported eating on a survey from a few decades ago. So it more represents vaguely what the average person reported that ate 33 years ago than something that is in theory an actually recommendation for what you should eat.
From US News:
….not only was the calorie standard not derived based on prevalent scientific equations that estimate energy needs based on age, height, weight and physical activity levels, but the levels were not even validated to ensure that the self-reported ranges were actually accurate.
In general I believe there’s multiple studies out there that suggests that self-reported food consumption tends to systematically underestimate what was actually consumed - for example “Traditional Self-Reported Dietary Instruments Are Prone to Inaccuracies and New Approaches Are Needed”
Plus people’s needs vary a lot based on at least demographic and behavioural factors. There are plenty of people for which 2000 is substantially more than would be recommended if their goal was to maintain their current weight.