The impact of cash transfers to poor women in Colombia on BMI and obesity: prospective cohort study

Abstract

Introduction: Prevalence of obesity is rising in Latin America and increasingly affecting socially disadvantaged groups, particularly women. Conditional cash transfers are recently established welfare interventions in the region. One, Familias en Accion, transfers ∼20% of average monthly income to women in Colombia's poorest families. Previous work has found that families buy more food as a result. We tested the hypothesis that participation in Familias would be associated with increasing body mass index (BMI) in participating women.

Methods: Women from participating areas and control areas (matched on environmental and socioeconomic criteria) were surveyed in 2002 and 2006. Pregnant, breast-feeding or women aged <18 or with BMI <18.5 kg m(-2) were excluded. The sample comprises 835 women from control and 1238 from treatment areas. Because some treatment areas started Familias shortly before baseline data collection, a dummy variable was created that identified exposure independent of time point or area. Follow-up was 61.5%. BMI was measured by trained personnel using standardized techniques. Overweight was defined as BMI ≥ 25 kg m(-2) and obesity as ≥ 30 kg m(-2). The effect of Familias was estimated using linear regression (or logistic regression for dichotomous outcomes) in a double-difference technique, controlling for several individual, household and area characteristics, including parity and baseline BMI, using robust standard-errors clustered at area-level in an intention-to-treat analysis.

Results: At baseline, women's mean age was 33.3 years and mean BMI 25.3 kg m(-2); 12.3% women were obese. After adjustment, exposure to Familias was significantly associated with increased BMI (β=0.25; 95% confidence interval (CI) 0.03, 0.47; P=0.03). Age (β=0.09; 95% CI 0.06, 0.13; P<0.001) and household wealth (β=0.78; 95% CI 0.41, 1.15; P<0.001) were also positively associated with BMI. Familias was also associated with increased odds of obesity (odds ratio (OR)=1.27; 95% CI 1.03, 1.57; P=0.03), as was age (OR=1.04; 95% CI 1.02, 1.06; P=0.001).

Conclusion: Conditional cash transfers to poor women in Colombia are independently associated with increasing BMI and obesity risk. Although conditional cash transfers are generally regarded as popular and successful schemes, parallel interventions at individual, household and community level are needed to avoid unanticipated adverse outcomes.

Figure 1

Participant flow-chart (this could appear as web supplementary material)

Figure 2. crude BMI (kg/m², 95% CI) and double-difference*

*Women from pre-exposed areas not included; differences inexact due to rounding.

Figure 3. crude prevalence (%, 95% CI) of overweight and double-difference *

*Women from pre-exposed areas not included; differences inexact due to rounding.

Figure 4. crude prevalence (%, 95% CI) of obesity and double-difference