Measuring intra-household health inequality: explorations using the body mass index

This paper examines the relationship between level of well-being and inequality at inter-country and intra-household levels, using individuals' body mass index (BMI) rather than income as the indicator of well-being. BMI is useful for these purposes because (1) it is measured at the individual rather than household level; (2) it reflects command over food, but also non-food resources that affect health status like sanitary conditions and labour-saving technologies; (3) it accounts for caloric consumption relative to needs; (4) it is easily measured; and (5) any measurement error is likely to be random. We do not find any evidence to support the idea of an intra-household or inter-country Kuznets curve. We study the correlations between average household well-being, still measured by BMI, and differences in the BMIs of males and females, parents and children. Here, we find a tendency to protect the BMI of young children when living standards are very low. We find no clear patterns by gender. Perhaps the most striking finding in the paper is that about half of total BMI inequality at the country level is within households. Thus, standard measures of inequality that use household-level data may drastically understate true inequality.