Calories REALY depend on several factors.
As an athlete I was eating 12,000 per day and barely managing.
I've also done 'well' on 800 a day
I've also been a mess on 800 per day.
A 2litre of coke has about 800 per day. So does gorging on sushi.
12,000 per day on 80% protein? Or 12,000 per day on 80% fat?
And those are just 2 variables amongst MANY. (# and type). There are 12 variables that plug into my hospital nutritionist software program (with several score variables per 12 main categories). Any program that has fewer than 10 variables is only a partial picture. Any that just has ONE (age, for example) is a massive generality.
Age
Height
Weight
Body type
Activity level
Type of activity
Length(s) of activity
Pre existing conditions
Climate
Medications
Food source (fresh, fresh cooked in WHICH WAY, frozen, dried, canned, marinated, pickled, mass produced, etc.)
TYPE of general diet (omnivorous, vegetarian, pescatarian, octolavo, vegan, kosher, etc.)
Are the BARE basics in determining diet and expected caloric and content needed.... Because they all affect our physiology. OTHER factors (also in the software, which is still an actuary type thing based off of stats which can be wrong for an individual)... Include
Eating alone
Eating with people you like
Eating with people you dislike
Time of day (in comparison with activity, type, and length)
Dress (this goes with climate, both being a HUGE game changer)
ETC