Short-Term Anthropometric BMI Elasticity to Expected Labor Returns
RCTClinical Trial
Child health interventions and intrahousehold resource shifts produce distinct biological responses across different time horizons, making it difficult to distinguish immediate caloric and health investments from cumulative long-term skeletal growth changes.
Picture this
Think of a sapling in a garden: giving it better fertilizer and extra water every day will immediately thicken its leaves and trunk within a few months, but making the tree grow noticeably taller takes many years of uninterrupted nourishment.
What the evidence says
Treatment significantly increased girls' body mass index (BMI) for age z-scores by 0.24 standard deviations (p < 0.01), whereas height-for-age z-scores showed no statistically significant change (+0.04 SD, p > 0.10), reflecting rapid weight and nutritional adaptation over a three-year window.
- Who was studied
- 2,031 young girls aged 5–15 across 160 rural Indian villages.
- How
- Randomized field trial collecting physical anthropometric measurements (height and weight) to calculate WHO standardized age-adjusted z-scores over a three-year intervention period.
What to do
Utilize body mass index (BMI) z-scores rather than height-for-age z-scores when evaluating short-to-medium term nutritional improvements in child health interventions.
From the source
"The treatment led to a statistically significant increase in BMI-for-age z-scores for girls... However, there was no statistically significant effect of the treatment on height-for-age z-scores."
517 labor market opportunities QJE April '12.pdf