Average Caloric Requirements and Physical Activity

Most analyses of hunter-gatherer diets assume caloric intakes of approximately 3000kcal/day

(1,4) a surprisingly large figure that exceeds typical contemporary intakes. The level of energy

expenditure necessitated by pre-agricultural lifestyles, however, was much greater than that for

average modern individuals. For instance, total energy expenditure in the !Kung and Ache

peoples averaged 206kJ/kg/d, compared to roughly 134kJ/kg/d for contemporary humans (13).

This difference is accounted for both by the fact that hunter-gatherers had, on average, higher

resting metabolic rates, due to greater proportions of lean to adipose tissue, as well as greater

levels of vigorous physical activity. Typical !Kung and Ache males have been estimated to

expend an average of 105kJ/kg/d in the course of their regular occupations; to compete with such

a figure, the sedentary male of today would have to walk approximately 19km/d in addition to

his other pursuits (12).

It is probably as a result of their increased energy throughput (moderately elevated caloric intake

coupled with greatly increased energy expenditure) that the health consequences of metabolic

imbalance occurred only rarely in non-acculturated hunter-gatherers. Unlike contemporary

Americans, hunter-gatherer groups practicing traditional lifestyles showed little tendency toward

obesity, non-insulin dependent diabetes mellitus, and other associated disorders (8). The process

of acculturation, however, has been found to greatly increase the prevalence of such diseases in

hunter-gatherer groups, as indicated by the recent experiences of Australian Aborigines (14), the

Pima Indians of the American southwest (15), and others.