[tjogin]

> Are you arguing that there were no societies that had caloric surplus up until late in the XX century?

No, only that a caloric surplus is necessary to gain weight. Matter cannot be created from nothing, a surplus of energy is required to perform all the bodily functions and to also build body mass.

A people can have an abundance of food and still not get obese, if they simply don't eat too much of it, relative to their caloric expenditure.