Wikipedia informs us that “obesity is a medical condition in which excess body fat has accumulated to the extent that it may have a negative effect on health, leading to reduced life expectancy and/or increased health problems.” People in these conditions have a body mass index (BMI) that exceeds 30 kg/m2, where the BMI is obtained by dividing a person’s weight (in kilograms) by the square of the person’s height (in metres).
Obesity is on the rise all over the world: previous studies, mostly focused on low- and medium-income countries, have shown that the number of people with obesity increases with the gross domestic product (GDP) of a country, and that education can be an important factor in this context.
Recent data now sheds new light on the phenomenon.
Relationship between education, obesity and GDP
A research study on obesity has just been completed covering 70 countries, including a number of high-income countries (Kinge et al., 2015), with data spanning the period 2002–2013 (Table 1). The results confirm that obesity, education and GDP are indeed related, however their association is relatively complex. The prevalence of obesity increases with GDP, but, and this is the novelty, only (or, at least, much more severely) among individuals with lower levels of education: there is no statistically significant increase in obesity among those with higher education. In practice, this means that in countries with low GDP obesity is more prevalent among those with high education, while in countries with high GDP it is relatively more frequent among those with low education (Figure 1).
The study also found that the relationship appeared to be more marked among women than among men, even if it did not actually test whether the differences between genders were statistically significant.
A possible explanation of the rationale behind this finding is suggested directly by Jonas Minet Kinge¹, one of the authors of the research.
“When countries become richer, changes in living conditions occur that predominantly affect the weight of those with low education. For example, earlier studies suggest that low education in poorer countries is associated with limited resources available for excess food consumption, and more physically demanding work. These conditions limit obesity among those with low education in developing countries.
In rich countries with economies based largely on service and technology industries, most people can afford calorie-rich foods and there are, overall, fewer jobs with physically demanding work. This boosts the prevalence of obesity among those with lower education in high GDP countries.”
The reason why the association was found to be more pronounced in women than in men is less clear: the most likely explanation is that that women and men often have different educational backgrounds and professions, and that they experience different norms and ideals from their society.
About the study
The researchers collected data about individuals’ education, age, gender, height and weight from 70 different countries, and analyzed the association between obesity and GPD by education, using different statistical methods. Both absolute and relative educational categories were used, and the results did not change appreciably.
It is important to emphasize that the study did not study causality: the researchers could not determine, for example, whether it is education or GDP that affects obesity or vice versa. Neither could they rule out that the results were influenced by other factors not included in the study. Another limitation of the study is that it used self-reported height and weight, which is not optimal but is considerably more practical, when it comes to data collection.
The study was conducted in collaboration between researchers at the Norwegian Institute of Public Health, the University of Oslo and the University of Bergen in Norway, and Columbia University in the USA.
Kinge JM, Strand BH, Vollset SE and Skirbekk V (2015) Educational inequalities in obesity and gross domestic product: evidence from 70 countries. Journal of Epidemiology and Community Health, doi: 10.1136 / Jech-2014-205353
¹Kinge is a researcher at the Norwegian Institute of Public Health and also Associate Professor at the Department of Health Management and Health Economics at the University of Oslo.