Serum leptin levels and anthropometric correlates in Ache Amerindians of eastern Paraguay

Abstract

Leptin is a recently discovered peptide hormone secreted primarily from adipocytes in humans and other mammals; it is a reflection of fat stores, and has been associated with reproductive function. However, few leptin measurements are available from nonindustrialized populations, including contemporary hunter/gatherer communities undergoing the transition to sedentary agriculture. This investigation reports single-sample serum leptin measurements in healthy Ache Amerindian males (n = 21; average age, 32.8 +/- 3.4 SE) and females (n = 12; average age, 31.3 +/- 4.3) in eastern Paraguay. Ache leptin concentrations were much lower than in industrialized populations, although significant sexual dimorphism was evident (female 5.64 ng/ml +/- 0.91 SE vs. male 1.13 ng/ml +/- 0.08; P < 0.0001). Indeed, female leptin levels were similar to those of anorexic women, despite apparently adequate adiposity. Controlling for fat percentage, no significant sex difference was evident, suggesting that adiposity was the primary source of leptin variation. Body fat percentage was highly correlated with leptin in females (r2 = 0.72; P < 0.0005) but not males, who exhibited a modest negative correlation (r2 = 0.25; P < 0.03). Weight (r2 = 0.45; P = 0.02) and BMI (kg/m2) (r2 = 0.81; P < 0.0001) were also significantly correlated in females but not males. These results suggest that: 1) clinical leptin norms based on industrialized populations may represent the highest range of human variation and may not be representative of most human populations; 2) hormonal priming may underlie population variation in leptin profiles; and 3) the relative importance of leptin as a proximate mechanism regulating reproductive effort during human evolution may have been modest.

Thrifty genes for obesity, an attractive but flawed idea, and an alternative perspective: the ‘drifty gene’ hypothesis

“…I have previously summarized some data on the body condition of modern hunter gatherer and subsistence agriculture communities (for example, references [59][60][61][62][63] showing that between famines these people do not get fat. 22,23 However, one could make the argument that these are the wrong populations to investigate because these societies have never developed organized agriculture, and so have never been exposed to 'real famines' sensu.…”

Serum leptin levels in Ache Amerindian females with normal adiposity are not significantly different from American anorexia nervosa patients

“…Storage and handling procedures have been previously described (Bribiescas, 2001). Serum samples were collected from anorectic and controls subjects using standard phlebotomy methods as described in Grinspoon et al (1996).…”

“…Curiously, Ache female leptin levels are similar to American anorectic patients despite adiposity that is commonly indicative of much higher leptin levels seen in healthy non-anorectic women (Bribiescas, 2001). This investigation tests the hypothesis that Ache women exhibit leptin levels that are not significantly different from anorectic patients, perhaps providing support for the role of chronic environmental differences that may alter leptin physiology.…”

“…Recently, a wide range of population variation has become evident, independent of adiposity. For example, the Ache of Paraguay exhibit among the lowest leptin levels reported of any population (Bribiescas, 2001).…”

Endocrinology, energetics, and human life history: A synthetic model

“…Studies of human leptin and ghrelin levels in the field have produced some 156 notable results, particularly highlighting population variation in average levels 157 (Bribiescas, 2001 general, subjects in non-western populations and populations engaged in subsistence 160 economies have significantly lower levels of both appetite regulating hormones than in 161 western, developed societies. This is true for leptin even after correcting for fat mass.…”