India is one of the world's most dynamic economic success stories of recent decades, but academics, economists and sociologists have been puzzled by a strange and paradoxical phenomenon that has accompanied this increasing prosperity: As average income is rising, Indians, on a per capita basis, are eating less and less. This long-observed trend is known to economic development experts as India’s "calorie-consumption puzzle."

According to data collected by Deepankar Basu and Amit Basole, of the economics department at the University of Massachusetts-Amherst, in their March study, “The Calorie Consumption Puzzle in India: An Empirical Investigation,” over the past three decades, the average per capita calorie intake has plunged while real per capita monthly expenditure, or MPCE, has increased.

According to a report by Quartz, an American business-focused digital news outlet, observers have proposed a number of explanations for this odd development, including the massive shift in India from labor-intensive agricultural jobs to sedentary urban white-collar work (which requires fewer calories).

Another possibility that has been floated suggests that, with higher per capita income, individuals are spending more on expensive food, lowering their overall caloric intake. Or perhaps Indians with significant incomes are simply spending more on non-food items, while diversifying their diets away from traditionally cheap cuisines. Other theories include entrenched poverty in rural areas (that is, very poor folk who simply cannot afford the higher food prices and therefore eating less).

But, Basu and Basole’s study also found that both rural and urban households in India have been contributing more of their monthly budgets to non-food-related expenses like rent, health care and schooling. This is likely a direct result of Indian government policy, which does not provide much public support for education and other services.

As a result, while India may be experiencing greater economic prosperity, for India’s poorest, things have remained bleak.

“The situation for poor Indians has surely worsened since the 1990s,” Ranjit Goswami, dean at the Institute of Management Technology in Nagpur India, wrote, noting that overall economic growth has not translated into lifting the nation’s most in need out of poverty. Indeed, the majority of rural Indians are consuming well below 2,400 kilocalories per day, which is the national threshold for rural poverty.