The upper class (doctors, lawyers) consumed more food then the working class because they could afford it, yet there was no obesity.
It's not about calories.
It's not about sugar.
It's the PUFAs making us fatigued and sick.
PUFAs are the evolutionary signal for the coming winter and they reduce our metabolic rate which ultimately leads to sickness.
All mammals seek PUFAs when they want to go into hibernation and if you give them a PUFA free diet they will burn through their fat-stores within days.
Listen to this for the quote in the subject: https://youtu.be/QmNzV15Wads?list=PL_7Y5WbwJV_uFMcCRNFbEhmEfV9bLyw2m&t=2142
Then listen to the whole conversation or start at 24:40 to skip the first topic which is specifically about kids.
There are two great channels: "David Gornosksi Fan Favorites" and also "Danny Roddy".
These are the people they have lot's of conversations with:
Brad Marshall (Ex-Keto. Cook, Pigfarmer, Geneticist.) https://fireinabottle.net/
Dr. Ray Peat (Ph.D. in Biology) http://raypeat.com/
Georgie Dinkov http://haidut.me/
The whole concept of a "food calorie" probably has some relation to the use of energy in the body, but it is certainly not direct and may be entirely useless. Calories in food are measured using a device called a "bomb calorimeter", which measures the total heat content of a food sample by reducing it to ashes.
Does your digestive system function like a bomb calorimeter? If it does, I suggest you go see a doctor.
And he will give you all kinds of great advise to keep you healthy.
Of course! Who could doubt it? He's got a white coat and "Doctor" in front of his name and everything.