Global trends in obesity

B.M. Popkin    University of North Carolina, USA

1.1 Introduction

This chapter explores shifts in nutrition transition from the period termed the receding famine pattern to one dominated by nutrition-related noncommunicable diseases (NR-NCDs). It examines the shifts in obesity and the speed of these changes, summarizes dietary and physical activity changes and provides some sense of the health effects and economic costs. The focus is on the world but special emphasis is given to the less understood shifts occurring in the lower- and middle-income countries of Asia, Africa, the Middle East and Latin America. This chapter shows that changes are occurring at great speed and at earlier stages of countries’ economic and social development. The burden of disease from NR-NCDs is shifting towards the poor and the costs are also becoming greater than those for undernutrition. Elsewhere, we cover in detail the stages of the nutrition transition and underlying conceptual framework (Popkin, 2003).

The major themes covered in this chapter are:

• The shift in the stages of the nutrition transition are occurring rapidly and this is seen in the speed of change in obesity around the world.

• The prevalence rates and dynamic shifts in obesity in the developing world match if not exceed those in the higher income countries.

• Dietary shifts are occurring that are fairly comparable across the developing world but different from those found in the USA and in other developed countries.

• Physical activity patterns, while much less studied, appear to be changing equally dramatically.

• The burden of obesity is shifting rapidly toward the poor and lower socio-economic status groupings.

• Income growth, long-term declines in food prices, urbanization and rapid dissemination of mass media are key determinants.

• The future trends appear to be as fast if not faster than current ones.

• The requirement for large-scale programme and policy action is great.

1.2 Trends in obesity

In a series of papers published in a recent issue of Public Health Nutrition (available as pdf files in the Bellagio papers section of www.nutrans.org), the current levels of overweight in countries as diverse as Mexico, Egypt and South Africa are shown to be equal or greater than those in the United States. Moreover, the rate of change in obesity in lower- and middle-income countries is shown to be much greater than in higher-income countries (see Popkin, 2002, for the overview). Figure 1.1(a) presents the level of obesity and overweight in several illustrative countries. Most interesting is the fact that many of these countries with quite high overweight levels are very low- income. Moreover, it probably surprises many people that the levels of obesity of several countries – all with much lower income levels than the USA – are so high.

Figure 1.1(b) shows how quickly overweight and obesity status has emerged as a major public health problem in some of these countries. Compared with the USA and European countries, where the annual increase in the prevalence of overweight and obesity is about 0.25 for each, the rates of change are very high in Asia, North Africa, and Latin America – two to five times greater than in the USA.

The burden is shifting towards the poor! We show that a large number of low- and moderate-income countries already have a greater likelihood that adults residing in lower-income or lower educated households are overweight and obese relative to adults in higher income or education households (Monteiro et al., 2004). This study, based on multi-level analysis of 37 nationally representative data sets, shows that countries with a GNP per capita over about $2500 are likely to have a burden of obesity greater among the poor. It also provides some idea of the set of risk factors causing obesity and other NCDs that are changing rapidly, including poor diets, inactivity, smoking and drinking.

These changes are occurring in both urban and rural areas. In one recent paper in which we examined overweight and obesity in nationally representative cross-sectional surveys on women aged 20–49 (n = 148579) conducted from 1992 to 2000 in 36 developing countries from all regions and stages of economic development (Mendez et al., 2005). We examined associations between the nutritional status of urban and rural women with national socioeconomic development indicators – gross national income (GNI) and urbanization. Many countries had high levels of overweight in both urban and rural women. Overweight exceeded underweight in the great majority of countries: the median ratio of over- to underweight was 5.8 in urban and 2.1 in rural areas. Countries with high GNI and urbanization levels had not only high absolute levels of overweight, but small urban–rural differences in overweight and very high ratios of over- to underweight. However, even many of the poorest countries also had fairly high levels of rural overweight, and ratios of over- to underweight ≥ 1.0.

1.3 Dietary shifts: more fat, more added caloric sweeteners, more animal source foods

The diets of the developing world are shifting rapidly, particularly with respect to fat, caloric sweeteners and animal source foods (Popkin, 2003; Popkin and Du, 2004).

1.3.1 Edible oil

In the popular mind, the Westernization of the global diet continues to be associated with increased consumption of animal fats. Yet the nutrition transition in developing countries typically begins with major increases in the domestic production and imports of oilseeds and vegetable oils, rather than meat and milk (see Drewnowski and Popkin, 1997 for details). Fat intake increases with income, but there have also been dramatic changes in the aggregate income–fat relationship (Du et al., 2004). Most significantly, even poor nations had access to a relatively high-fat diet by 1990, when a diet deriving 20% of energy (kcal) from fat was associated with countries having a GNP of only $750 per capita. In 1962, the same energy diet (20% from fat) was associated with countries having a GNP of $1475 (both GNP values in 1993 dollars).

This dramatic change arose principally from a major increase in the consumption of vegetable fats. In 1990, these accounted for a greater proportion of dietary energy than animal fats for countries in the lowest 75% of countries (all of which have incomes below $5800 per capita) of the per capita income distribution. The change in edible vegetable fat prices, supply, and consumption is unique because it affected rich and poor countries equally, but the net impact is relatively much greater on low-income countries.

1.3.2 Caloric sweeteners

Sugar is the world’s predominant sweetener; however, we use the term caloric sweetener instead of added sugar, as there is such a range of nonsugar products used today. High fructose corn syrup is a prime example as it is the sweetener used in all US soft drinks. The overall trends show a large increase in caloric sweetener consumed (see Popkin and Nielsen, 2003). In 2000, 306kcals were consumed per person per day, about a third more than in 1962; caloric sweeteners also accounted for a larger share of both total energy and total carbohydrates consumed. All measures of caloric sweetener increase significantly as GNP per capita of the country and urbanization increase. However, the interaction between income growth and urbanization is important.

1.3.3 Animal source foods

The revolution in animal source foods (ASF) refers to the increase in demand and production of meat, fish, and milk in low-income developing countries. The International Food Policy Research Institute’s Christopher Delgado has studied this issue extensively in a number of seminal reports and papers (summarized in Delgado, 2003; Delgado et al., 1999). Most of the world’s growth in production and consumption of these foods comes from the developing countries. Thus, developing countries will produce 63% of meat and 50% of milk in 2020. It is a global food activity, transforming the grain markets for animal feed. It also leads to resource degradation, rapid increases in feed grain imports, rapid concentration of production and consumption and social change.

1.4 Physical activity changes at work, leisure, home, and travel

There are several linked changes in physical activity occurring jointly. One is a shift away from the high energy expenditure activities such as farming, mining and forestry towards the service sector. Elsewhere, we have shown this large effect (Popkin, 1999). Reduced energy expenditures in the same occupation are a second change. Other major changes relate to mode of transportation, home production and activity patterns...