Assessing the linkages between low body mass index and morbidity in adults: evidence from four developing countries.

The study explores the relationship between low BMI and illness patterns in four developing countries. Using probit analysis, the study finds small but statistically significant effect of low BMI on proneness to morbidity in Pakistan and Kenya but none in the Philippines and Ghana. The circularity of causation between low BMI and illness was addressed by using the instrumental variable approach. The study also finds that the threshold at which morbidity begins to rise is not consistent with the suggested cut-off of BMI 18.5 kg/m2. The cut-offs were meaningful only in the case of Pakistan, but even here, the sizes of relationships are quite small although statistically significant.