Weight of nations: a socioeconomic analysis of women in low- to middle-income countries

Abstract

Background: The increasing trend in body mass index (BMI) and overweight in rapidly developing economies is well recognized.

Objective: We assessed the association between socioeconomic status and BMI and overweight in low- to middle-income countries.

Design: We conducted a cross-sectional analysis of nationally representative samples of 538,140 women aged 15-49 y drawn from 54 Demographic and Health Surveys conducted between 1994 and 2008. BMI, calculated as weight in kilograms divided by height squared in meters, was specified as the outcome, and a BMI (in kg/m(2)) of ≥25 was additionally specified to model the likelihood of being overweight. Household wealth and education were included as markers of individual socioeconomic status, and per capita Gross Domestic Product (pcGDP) was included as a marker of country-level economic development.

Results: Globally, a one-quartile increase in wealth was associated with a 0.54 increase in BMI (95% CI: 0.50, 0.64) and a 33% increase in overweight (95% CI: 26%, 41%) in adjusted models. Although the strength of this association varied across countries, the association between wealth and BMI and overweight was positive in 96% (52 of 54) of the countries. Similar patterns were observed in urban and rural areas, although SES gradients tended to be greater in urban areas. There was a positive association between pcGDP and BMI or overweight, with only weak evidence of an interaction between pcGDP and wealth.

Conclusion: Higher BMI and overweight remain concentrated in higher socioeconomic groups, even though increasing BMI and overweight prevalence are important global public concerns.

FIGURE 1.

Association between BMI and wealth quartiles by urban or rural area of residence for women across 54 low- and middle-income countries. Note: The interaction test was significant at P < 0.0001. The patterns were similar when we considered the likelihood of having a BMI (in kg/m²) ≥25 (overweight) as the outcome. Statistical tests were based on a 2-tailed Wald test using chi-square distribution.

FIGURE 2.

Association between BMI and per capita Gross Domestic Product by wealth quartiles for women across 54 low- and middle-income countries. Note: P values for the interaction test between the second-richest, third-richest, and richest quartile per capita Gross Domestic Product were 0.0005, 0.162, and 0.062, respectively, compared with the poorest quartile. The patterns were similar when we considered the likelihood of having a BMI (in kg/m²) ≥25 (overweight) as the outcome. Statistical tests were based on a 2-tailed Wald test using chi-square distribution.