But in an End-of-Days / TEOTWAWKI Your BMR would be increased due to increased physical movement ( calorie burn ) , No Gas Central Heating on all the time ( Calorie Burn ) and a general increase in all activitys will increase the BMR.
No more sedentry lifestyles available, I'm afraid.
Speak for yourself. Depends on the circumstances how much activity the H-G does. If you lived next to a salmon river with huge runs then for part of the year you need do hardly anything. But, of course the general level of activity would rise with wood getting etc. One might wonder though what the wives and children were for if one had to do the bulk of the hard work. Would society re-sort itself and maintain equality of work amongst the genders or would the age-old pattern assert itself. Must make it clear that I am not advocating such a situation just speculating.
What is certain that children could not be kept in the present infantile state many of them are today until they are 18 or older but they would have to be handling sharp things and fire from their early years as well as getting part of their own food. Things of course that Bushcraft encourages anyway which is one of its benefits.