Per study data published in Obesity, even slight increases in the availability of energy-dense foods promoted weight gain and obesity among Tsimane’ forager-horticulturalists in Bolivia. Although the study population had moderate levels of physical activity and a subsistence-based diet, increased access to market-purchased cooking oil and animal products was still found to increase adiposity.

The Tsimane’ Amazonian Panel Study sought to investigate the effect of modernization and market exposure on the health of Bolivia’s Tsimane’ forager-horticulturalists. Between 2002 and 2010, annual data assessments were conducted in 13 communities of Tsimane’ throughout Bolivia. The pooled sample comprised 365 men and 339 nonpregnant women who were ≥20 years of age. Participants each provided a mean of 5 observations across the 9-year study period. Associations between household dietary intake and adiposity were assessed. Measures of adiposity included body mass index (BMI), body fat percentage, and waist circumference. Dietary intake was estimated using 1-week retrospective reports by the head woman of each household. Foods were characterized as either traditional or modern/market foods; traditional foods comprised homegrown or hunted game, whereas market foods included domesticated animal products, market grain products and sugar, and cooking oil. Linear mixed-effects models were conducted separately for men and women and used to estimate the relationship between diet and adiposity. Covariates included educational attainment, Spanish proficiency, household income and wealth, and distance from a market center.

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During the study period, the odds of becoming overweight or obese increased by 14% for Tsimane’ men and women (95% confidence interval [CI], 1.03-1.26) and 37% (95% CI, 1.13-1.66), respectively (both P =.001). The average (± standard error) annual increase in BMI was 0.60%±0.12% (P <.001) for women and 0.22% ± 0.09% (P =.009) for men. The prevalence of women who were overweight or obese increased from 22.6% and 2.4% in 2002 to 28.8% and 8.9% in 2010, respectively. The prevalence of men who were overweight or obese increased from 16.2% and 0.7% to 25.0% and 2.2%, respectively.

Household caloric intake did not increase significantly between 2002 and 2010, and homegrown crops remained the primary source (≥61%) of calories during the study period. However, the odds of using cooking oil increased by 24% each year (95% CI, 1.19-1.29; P <.001). Cooking oil use was positively associated with BMI among women, although not for men. Consumption of domesticated animal products did not increase significantly between 2002 and 2010, although each available household serving was associated with 57% increased odds of BMI ≥25 kg/m2 among women (95% CI, 1.16-2.12; P =.003) and a 0.25%±0.10% increase in waist circumference among men (P =.008).

These results suggest that even with high daily levels of physical activity and an overall low-fat diet, the Tsimane’ were vulnerable to adiposity gains with increased consumption of energy-rich foods. The effects on adiposity were not uniform between food categories, with cooking oil contributing more significantly than refined grains or sugar. Changes in adiposity also differed between men and women. Overall, these data offer perspective on the effect of market-based foods on otherwise subsistence-based populations.

Reference

Bethancourt HJ, Leonard WR, Tanner S, Schultz AF, Rosinger AY. Longitudinal changes in measures of body fat and diet among adult Tsimane’ forager-horticulturalists of Bolivia, 2002-2010. Obesity (Silver Spring). 2019;27(8):1347-1359.