Countries with high rates of inequality, including the U.S. and Portugal, also have high rates of obesity. So is there a relationship between the two things? Do wealth gaps cause people to eat more and put on more weight?
A new study from Scotland provides causal evidence for what researchers have long suspected: When people feel themselves to be substantially poorer than others in society, they're likely to up their caloric intake.
There are two main reasons for that, the study says. First, if you see yourself as poor, there's a tendency to "feed forward" to compensate for future calorie shortages. Much like animals in the wild, people will eat more in environments of perceived scarcity.
Second, poverty induces anxiety, and anxiety leads to overeating, as anyone who has been anxious (or poor) knows. People who are anxious, irrespective of their income level, have a tendency to reach for the cookie jar, a large number of studies have shown.
But researchers were interested in testing these hypotheses in an experimental setting. In one experiment, 54 undergraduate volunteers were induced to feel either richer or poorer than their peers. Then they were given a mix of crackers and chocolate to eat as they watched two National Geographic-type videos. The poor group consumed 54% more calories than the rich group.
A second experiment, involving 93 undergraduates, tested whether the inequality-obesity link has a social component. That is, are people more likely to eat when they're poor if they care about what other people think of them? As before, the volunteers watched two videos while snacking. But this time they were asked to fill in questionnaires ahead of time, asking about their relative social position and how much they cared about this. Then they were told they would have to participate in a group discussion where their status would be revealed.
The researchers were trying to induce anxiety to see what effect it would have on food choices, and, indeed, it did have an effect. "The anxiety linking inequality to increased food intake in these two studies has a decidedly social flavor," the paper says. "It is a fear of negative social evaluation due to a downward or upward social comparison. ... People’s chronic need to affiliate with others amplifies this link."
Interestingly, richer participants also felt anxious about their social position and ate more than average. "Those who have what others desire may fear being envied and challenged over the legitimacy of their privileged position," the researchers say. In other words, inequality may also be bad for richer people in society, even though obesity is overwhelmingly a problem among the poor.
The study was led by Boyka Bratanova at the University of St Andrews, and is published in the journal Appetite. "Our findings suggest that the well-known ... link between socioeconomic conditions and obesity may be underpinned by the psychology of human emotions and social motives," the researchers say.