For most people in rich countries hunger is a temporary inconvenience, easily solved by popping out to the shops or raiding the fridge. But chronic hunger is part of everyday life for many people in poorer places. Halving the proportion of people in developing countries who do not get enough to eat is one of the United Nations’ Millennium Development Goals.
Reducing hunger is a complicated task. There is no global shortage of food. Less poverty does not always mean better-nourished people. In India, for example, real incomes rose and the price of food fell between 1980 and 2005. Yet evidence suggests that Indians, even those who were originally eating less than recommended, reduced their calorie consumption in that time. Such findings have long puzzled economists.
A recent paper by two economists, Robert Jensen of the University of California, Los Angeles, and Nolan Miller of the University of Illinois, Urbana-Champaign, suggests that part of the problem may lie in the way governments and international agencies count the hungry. This typically involves fixing a calorie threshold—2,100 calories per day is a common benchmark—and trying to count how many people report eating food that gives them fewer calories than this number. Since calorific needs differ from person to person, a universal number is clearly only a guide. What’s more, concentrating on calories ignores the important role of micronutrients such as minerals and vitamins (see article). But the economists argue that this approach to measuring hunger also does not accord with how people themselves think about it. They propose a new way to use people’s eating choices to tell whether they are hungry.
Hunger is a physically unpleasant experience: it is accompanied by headaches, pain, dizziness, loss of energy and an inability to concentrate. For a hungry person, therefore, the extra utility from more calories is extremely high. The economists argue that the pain caused by hunger will prompt insufficiently nourished people to spend a larger share of their food budget on staples like rice and millet, which are cheap sources of calories. But once people are no longer hungry, they do not need to spend their incremental cash on the cheapest source of calories but can base their choices on things like variety and taste. This means that the share of calories that comes from staples falls progressively once a person is no longer famished; and that an unusually high share of calories coming from staples indicates that a person is hungry.
How high is unusually high? By looking at the prices of various foods, it is possible to work out what share of a person’s calories would come from staples such as rice and wheat if he were trying to fulfil his dietary needs as cheaply as possible. This theoretical “staple calorie share” (SCS) can then be compared with the make-up of a person’s actual diet. Someone who is consuming a significantly higher share of calories from staple foods than predicted is likely to be hungry.
This approach would be far too cumbersome if each person’s SCS varied greatly but things turn out to be considerably simpler. Using accepted dietary guidelines for people of various sizes and ages, and data on food prices for parts of China, the authors find that the share of calories that ought to come from staples varies much less than overall calorific needs. Wide variations in people’s age, sex, physical condition and lifestyle (more exercise, say) mean that some people need as little as 2,112 calories per day, while others may require as many as 3,202 calories. But the authors find that most calculated SCSs remain in a narrow band between 80% and 85% of overall calories. What this suggests is that someone getting less than 80% of his or her calories from a staple is past the point where conquering hunger is the primary motivation driving food purchases.
The economists use this threshold to measure the extent of undernourishment in nine Chinese provinces, where 16,000 individuals in 3,800 households were surveyed several times between 1991 and 2000. The people who were surveyed had to report everything they had eaten or drunk the previous day. The survey data conformed with the basic idea of substitution: the poorest households ate little other than staples. As income rose above a certain level, however, the SCSs dropped. People seemed to move out of the danger zone once their monthly income exceeded 225 yuan ($27 in 2000).
The data show how many people get less than four-fifths of their calories from rice, the main staple in most of the areas studied. Here, the results contradict what the Chinese government’s standard 2,100-calorie-per-day threshold would find. Around 67% of households in the sample were undernourished by the standard measure in 2000, but only 32% got more than 80% of their calories from staples. This is a big difference. Using data on people’s choice of what to eat leads to an estimate of hunger that is about half as large as the estimate using the standard method.
The two measures also give opposing results about long-term trends in hunger. The average household in the sample got richer between 1991 and 2000, but the fraction that consumed less than the mandated daily number of 2,100 calories actually rose, from 53% to 67%. The share of calories coming from staples points in a different direction, however: by this measure, the number of hungry households dropped from 49% to 32% over this period. More recent evidence suggests something similar. A 2008 study found that giving poor Chinese households subsidies on staple cereals failed to lead people to consume more rice or wheat. Instead, they ate more shrimp and meat. Not necessarily the cheapest source of calories, but considerably tastier.
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