Low energy expenditures in free-living populations

Low energy intakes are reported fairly frequently in populations where the implication is that these populations are free-living and that these intakes represent the norm. Intakes of energy, if they really reflect those pertaining to the average life-style, must also be reasonably indicative of energy expenditure. It is possible to define 'low' energy expenditure on the basis of obligatory metabolism (BMR + dietary induced thermogenesis) plus the energy needed for minimal physical activity--eg 2 h of standing activities and 1 h of walking daily. On that basis, the minimal realistic level is about 1.5 x BMR, and tables are given showing typical values for men and women over a range of body weights. If these values are accepted, considerable doubt must be placed on the interpretation of many reports in the literature of people apparently existing on 'low' energy intakes.