Do you actually have studies you can link to that can show this? With a quick search I see a study [1] that both acknowledges that data on hunter-gatherers is light and also finds that total energy expenditure (which I assume is what you mean by the "lifestyle" part of "lifestyle and diet") is roughly the same between this hunter-gatherer society and western cultures:
"Like other complex, continuous traits (e.g., stature), environment can clearly influence TEE, as is evident in the elevated energy expenditures of traditional farmers (Table 1). Nonetheless, TEE is remarkably similar across a broad, global sample of populations that span a range of economies, climates, and lifestyles (Fig. 1, ,2).2). Not only is TEE statistically indistinguishable between Westerners and Hadza foragers, but the range of TEE within Western, foraging, and farming populations largely overlap, both at the individual and population levels (Table 1, Fig. 1, ,2).2). We hypothesize that TEE may be a relatively stable, constrained physiological trait for the human species, more a product of our common genetic inheritance than our diverse lifestyles."