To investigate the Asian enigma, the phenomenon of relatively high levels of undernutrition among children and adult women in South Asia, despite more favourable records with respect to infant mortality, women’s education, food availability or other aspects of living conditions in comparison with, for example, sub-Saharan Africa.

Literature has been explored to identify countries outside South Asia that are home to sizeable population segments from different ethnic backgrounds, including people of South Asian and African descent, and to compare prevalence rates of undernutrition in combination with indicators of standard of living between these various population segments.

Data on adult undernutrition prevalence rates among population groups of different ethnic descent living in the same country (South Africa, Fiji and the USA) generally reveal the highest prevalence rates of low BMI among adults, males and females, from South Asian background. The relatively high rates of low BMI among adults from South Asian background cannot be explained by less favourable socio-economic characteristics, such as lower income or less access to food.

It is hypothesized that there exists among adults of South Asian descent an ethnic predisposition for a low BMI. Other factors that may contribute to high levels of undernutrition in South Asia are discrimination of women and a poor dietary quality of poor households’ food composition pattern. The question needs to be addressed whether the commonly used cut-off point for adult underweight (BMI < 18·5 kg/m2) is universally applicable or whether ethnic differences should be taken into account.