Eliminating open defecation in India would save the average person about 50 calories per day, according to research by Josephine Duh and Dean Spears, published in the November 2017 issue of the Economic Journal.

Their study of the link between the disease environment and people''s energy needs suggests that open defecation wastes a little bit of India''s food each day. Because people with intestinal diseases cannot absorb all the food they eat, they end up purchasing, cooking and consuming more calories than they would otherwise need to.

The researchers note that India inverts Engel''s Law, one of the oldest established facts in economics. The law – named after Ernst Engel, a 19th century German economist and statistician – holds that richer households spend more money on food than poorer households, but they also spend a lower proportion of their total budgets on food.

Engel''s historical law still holds in India today to the extent that, unsurprisingly, richer Indians in 2016 consume more calories than poorer Indians in 2016, on average. But there is also a puzzle, first documented by Angus Deaton and Jean Drèze: average calorie intake in India has been declining since the 1980s.

Using data from the National Sample Survey, they computed that in 1983, the average person in rural India ate 2,240 calories per day. By 2005, this had fallen by almost 200 calories to 2,047 calories per person per day. How could it be that a poor population, on becoming richer, is eating less?

One possibility is that people need a little less food, because they are losing less of it to disease than used to be the case. Although sanitation in India has not been improving as fast as we might like it to, open defecation has been declining slowly.

If people in India are not exposed to as much disease as they used to be, then their intestines will be healthier and better able to absorb the food they eat. If the average family in India is exposed to a little less intestinal disease today than in the 1980s, then they might be able to afford to eat fewer calories, and save that part of their food budget for something else that they want to buy.

The new study finds evidence for this idea in three different Indian data sources. The authors use two measures of the disease environment: open defecation and infant mortality. Their analysis shows that:

  • First, and most importantly, districts in India where infant mortality has been falling the most quickly over recent decades – that is, the districts with the fastest improvements – are, on average, also the districts where calorie consumption has declined the most.
  • Second, people living in Indian villages with more open defecation or greater local infant mortality rates also eat more calories, on average. In particular, people eat more, on average, in villages where children suffer more diarrhoea. But fever and cough (other common childhood symptoms that do not reflect intestinal disease) are unrelated to food consumption.
  • Finally, data in a unique survey from the 1980s (which measured calorie consumption and local open defecation, as well as providing a detailed description of the work a household does) verify that the relationship between disease and calorie consumption is not merely a misleading consequence of poor people working in more demanding jobs for which they need to eat more.

So: can a slowly improving disease environment account for the decline over time in calorie intake? Yes, but only partially. Duh and Spears conclude that a rough lower bound is that gradual improvements in disease can explain about a quarter of the decline, possibly more. These findings leave open the puzzle of what explains the rest.

This new evidence suggests that open defecation wastes a little bit of India''s food each day. Because people with intestinal diseases cannot absorb all of the food that they eat, many people purchase, cook and consume more calories than they would otherwise need to.

Although the effect of open defecation on any one household''s food budget is typically small, these small effects add up over a large population. If Duh and Spears''s estimates are approximately correct, then eliminating open defecation would save the average person in India about 50 calories per day.

''Health and Hunger: Disease, Energy Needs, and the Indian Calorie Consumption Puzzle'' by Josephine Duh and Dean Spears is published in the November 2017 issue of the Economic Journal. Josephine Duh is at the Brattle Group. Dean Spears is at the University of Texas at Austin and the Indian Statistical Institute. Both are part of r.i.c.e. – a research institute for compassionate economics.