Ultimately, obesity reflects energy imbalance, so the major areas for intervention relate to dietary intake and energy expenditure, for which the main modifiable component is physical activity. It is clear that large shifts in access to technology have reduced energy expenditure at work in the more labor-intensive occupations, such as farming and mining, as well as in the less energy-intensive service and manufacturing sectors 23
. Changes in transportation 24
, leisure, and home production 25
relate to reduced physical activity. In addition the complex interplay between biological factors operating during fetal and infant development and these energy imbalances exacerbates many health problems26
. Such changes have been well documented for China and are also found in varying manifestations in many countries.
Finding ways to increase physical activity across all age groups is important for public health, but options for increasing energy expenditure through physical activity may be limited in low- and middle-income countries. For instance, to offset any increase of about 110 kcal of food or beverage in average daily energy intake, a women weighing 54 kg must walk moderately fast for 30 minutes and a man weighing 82 kg for about 25 minutes. Such levels of physical activity may be too much to expect, and so diet modification is a key approach to lower obesity prevalence, particularly with the ongoing decline in physical activity and increase in sedentary time (unpublished data). The dietary dynamics represent a major set of complex issues. On the global level, new access to technologies (e.g., cheap edible oils, foods with excessive ‘empty calories’, modern supermarkets, and food distribution and marketing) and regulatory environments (e.g., the World Trade Organization [WTO] and freer flow of goods, services, and technologies) are changing diets in low- and middle-income countries. Accompanying this are all the critical issues of food security and global access to adequate levels of intake. Many populations focus on basic grain and legume food supplies, while the overall transition has shifted the structure of prices and food availability and created a nutrition transition linked with obesity as well as hunger. We have used detailed time use data along with energy expenditures and other data to examine past patterns and trends and predit until 2020 and 2030 patterns of physical activity and sedentary time in the US, UK, Brazil, China, and India (unpublished data).
Prior to exploring the dietary dimension, we consider an important biological factor affecting obesity and chronic diseases in rapidly developing countries in Asia and Africa. This factor is the biological insults suffered during fetal and infant development that may influence susceptibility to the changes described above, thus influencing the development and severity of chronic disease trends for these countries.
Developmental origins of health and disease: Special concerns for low- and middle-income countries
The patterns of change in dietary intake and energy expenditure related to the global nutrition transition are particularly important in the context of current theories of the developmental origins of adult disease. Based on three decades of research, we now recognize that susceptibility to obesity and chronic diseases is influenced by environmental exposures from the time of conception to adulthood. An extensive literature demonstrates that fetal nutritional insufficiency triggers a set of anatomical, hormonal, and physiological changes that enhance survival in a “resource poor” environment 27
. However, in a postnatal environment with plentiful resources, these developmental adaptations may contribute to the development of disease. Some of the strongest evidence on the long-term effects of moderate to severe nutrition restriction during pregnancy comes from follow-up of infants born after maternal exposure to famine conditions, such as those experienced in parts of Europe during World War II. For example, A. C. Ravelli and colleagues 28, 29
found higher rates of obesity in 50-year-old men and women whose mothers were exposed to the Dutch famine in the first half of their pregnancies, and G. P. Ravelli and colleagues (Ravelli, Stein et al. 1976) found obesity in 19-year-old men whose mothers experienced famine during their pregnancies. Similarly, a follow-up of Hmong refugee immigrants shows higher rates of central obesity among those raised in a war zone, with effects amplified in those who migrated to the United States compared to those living in a traditional rural setting 30
The developomental origins theory of mismatch fits closely with the broader issues of mismatch discussed by us below, issues that emerged in our early research1, 2
and later work.31–33
This theory of “mismatch,” that is, early nutritional deficits followed by excesses 34
, may be particularly important in low- and middle-income countries undergoing rapid social and economic changes, because economic progress amplifies mismatch 35
. Much of the literature on developmental origins of health and disease (DOHAD) focuses on chronic diseases. However, given the strong association of chronic diseases with obesity and in particular with central obesity, this evidence is highly relevant and provides a strong rationale for obesity prevention in populations that have experienced dramatic changes in the nutritional environment as a consequence of the nutrition transition.
Mechanisms are varied but may include affects on the number of nephrons in the kidney 36
, glucocorticoid exposure subsequent to maternal stress or poor nutritional status may program the insulin and hypothalamic-pituitary axes for high levels of metabolic efficiency 27
, and epigenetic changes. Maternal stress and specific aspects of diet (for example, intake of folate and other methyl donors) can affect DNA methylation and gene expression 37, 38,39
. Ongoing studies in places such as India are examining the role of maternal micronutrient intake on epigenetic changes that affect child adiposity 39, 40
. Research in India has provided other important insights. Indian infants with poorly nourished mothers are born with weight deficits, but in relative terms the deficits in lean mass are greater than those in adiposity. In later life, when consuming modern high-energy and high-fat diets, the previously “thin-fat” babies also have greater central adiposity 41, 42
It is apparent from studies of developmental origins of disease that there is a strong intergenerational component to health. While much of the literature on early origins of obesity and associated risk has focused on undernutrition, there is also substantial evidence that maternal overweight and obesity in pregnancy influence disease risk among offspring. For example, gestational diabetes is related to offspring body composition and increased risk of insulin resistance and diabetes in offspring 43, 44
. Thus there is concern about an intergenerational amplification of diabetes risk. Women who were malnourished as children are at increased risk of being centrally obese and having impaired glucose tolerance as adults. If these conditions affect a woman’s pregnancy, her offspring are now at increased risk of early development of obesity and diabetes. As obesity develops at younger and younger ages, the likelihood that adolescents and young women will experience pregnancy complications associated with gestational diabetes and hypertension will increase dramatically. There is growing evidence that maternal obesity, even without gestational diabetes, is a risk factor for child obesity through a pathway related to fetal overnutrition (see the review by CH Fall45
On the other end of the nutrition spectrum, short maternal stature acts as a physical constraint on fetal growth 46, 47
. And vitamin and mineral deficiencies and stunting may in turn relate to increased obesity risk 48
Beyond the fetal period, nutrition and other input to health in infancy, childhood, and adolescence are important determinants of adult body composition and obesity risk. In light of the large increases in overweight and obesity in children as well as adults, attempts have been made to determine the ages at which faster weight gain relates to later obesity. A large literature relates “rapid growth” during infancy to risk of obesity in later childhood and into adulthood 49
. In addition, rapid weight gain, particularly from mid-childhood on, is related to increased risk of elevated blood pressure or impaired fasting glucose in young adulthood in low- and middle-income countries 50
. Concerns have been raised about the promotion of rapid weight gain in children who are malnourished. In low-income countries catch-up or compensatory growth following a period of faltering growth is desirable, because it is associated with reduced morbidity and improved survival 51,52, 53
and better cognitive development 54
. A key concern is whether the benefits of faster growth in these settings outweigh the possible long-term risks. Based on the COHORTS analysis of children from five low- and middle-income countries, faster weight gain in the first two years of life has a number of benefits. It is associated with the development of lean body mass but not with increased risk of impaired fasting glucose or diabetes in young adulthood (papers of team under journal review: e.g., Kuzawa et al 55
). Given observations that patterns of child growth have important consequences for the development of obesity and chronic diseases, another line of research focuses on factors that contribute to or protect against early development of adiposity. In this regard, the potential programming roles of early diet have been explored, including the roles of breast-feeding and high intake of dietary protein, fat, and sodium. These topics are important in light of the dramatic changes in diet composition that characterize many populations in the developing world.
Of course, early feeding issues are important. Some studies show a protective effect of breast-feeding on later development of obesity and chronic diseases 56, 57
, while other studies show no effects 58
. Similarly consistently high protein intake during complementary feeding in the first two years of life has been associated with a higher mean BMI and percentage body fat at age seven in cohort studies of German children 59
, and other researchers have suggested a strong link between high protein intake and obesity 60
Dietary fat may also play a role in the development of NCDs in terms of both the amount of fat and the composition of fats. The STRIP study in Finland demonstrates that lower total and saturated dietary fat intake in infancy results in lower serum cholesterol, LDL-c, and triglyerides (as well as lower blood pressure) in children up to age 14, even without effects on height, weight, or BMI 61, 62
. Worldwide the increase in plant oil consumption has increased the intake of n-6 fatty acids and the ratio of n-6 to n-3 fatty acids. This is a concern, because high intake of n-6 fatty acids is associated with altered immune function, differentiation of preadipocytes into mature fat cells, and changes in fat deposition patterns. Another study relates high sodium intake from infant formula and weaning foods to increased blood pressure in adulthood 63
The knowledge emerging with the developmental origins research provides only one dimension of the shift toward greater obesity. While early life exposures and biological insults appear to enhance the adverse effects of dietary change, in the end shifts in energy balance and the entire structure of the diet have played major concomitant and separate roles. We speak first of broad trends and then return to the issues of poverty and availability. These link the set of dynamic changes in our food supply with food security.
It is useful to understand how vastly diets have changed across the low- and medium-income world to converge on what we often term the “Western diet.” This is broadly defined by high intake of refined carbohydrates, added sugars, fats, and animal-source foods. Data available for low- and middle-income countries document this trend in all urban areas and increasingly in rural areas. Diets rich in legumes, other vegetables, and coarse grains are disappearing in all regions and countries. Some major global developments in technology have been behind this shift.
Edible oil–vegetable oil revolution
Fats have major benefits in improving flavor. Some scientists suggest that the selection of fat- as opposed to carbohydrate-rich foods is primarily determined by brain mechanisms that may include central levels of neurotransmitters, hormones, or neuropeptides 1
. In the 1950s and 1960s in the United States and Japan, technology was developed to cheaply remove oils from oilseeds (corn, soybean, cottonseed, red palm seeds, etc.) 1
. Breeding techniques to increase the oil content of these seeds accompanied the shifts, and higher-income countries saw a large increase in the availability of cheap vegetable oils. This was followed by removal of the erucic acid from rapeseed oil to create healthier canola oil accompanied by extensive research on the good and bad components of each edible oil (e.g., trans fats and specific fatty acids). By 2010 inexpensive oils were available throughout the developing world. Between 1985 and 2010 individual intake of vegetable oils increased threefold to sixfold, depending on the subpopulation studied. In China, which has moderate but not high vegetable oil intake, persons age two and older now consume on average almost 300 calories and more than 30 grams of vegetable oil daily 64
The globe’s diet is much sweeter today than heretofore 65
. For example, 75 percent of foods and beverages bought in the US contain added caloric sweeteners and the average American aged 2 and older consumes about 375kcal/day 66, 67
. In the United States, one of the few countries where the added sugar in the diet is estimated 68
, research has shown a remarkable stability of added sugar intake from food over the last 30 years, while added sugar from beverages has increased significantly 66
. In 1977–78 two-thirds of added sugar in the US diet came from food, but today two-thirds comes from beverages. However, this may be an underestimate, as the USDA added-sugar estimate excludes fruit juice concentrate, a source of sugar that has seen major increases in consumption in the last decade and is now found in over 10 percent of US foods (unpublished data). Mexico, which experienced a doubling of caloric beverage intake to more than 21 percent of the kilocalories/day for all age groups from 1996 to 2002 is one of the few developing countries with data on caloric beverage patterns and trends 31, 69, 70
. While individual dietary intake data are not available for most low-income countries, national aggregate data on sugar available for consumption (food disappearance or food balance data) suggest that this is a major concern in all regions of the world 65
Shift toward increased animal-source food intake
Earlier research by C. L. Delgado and others at the International Food Policy Research Institute (IFPRI) found the beginning of a livestock revolution in the developing world 71
. Subsequent research by Popkin and others has shown major increases in production of beef, pork, dairy products, eggs, and poultry across low-and middle-income countries 72, 73
. Most of the global increases in animal-source foods have been in low- and middle-income countries. For example, India has had a major increase in consumption of dairy products and China in pork and eggs, among others.
The increase in animal-source food products has both positive and adverse health effects. On the one hand, for poor individuals throughout the developing world a few extra grams of animal-source foods can significantly improve the micronutrient profile of food consumed. On the other hand, excessive consumption of animal-source foods is linked with excessive saturated fat intake and increased mortality 74,75
Reduced intake of legumes, coarse grains, and other vegetables
While significant systematic research on the reduced consumption of these nutritionally important foods has not been undertaken, it is clear from case studies that consumption of beans, a vast array of bean products, and what we term often ‘coarse’ grains such as sorghum and millet has declined significantly 6, 76, 77
. This occurred from the 1960s through the 1980s in the United States and more recently across Asia and the rest of the Americas 78
Understanding the reasons for the trend toward increased consumption of animal-source food, oils, and caloric sweeteners and reduced consumption of legumes, coarse grains, and other vegetables begins with understanding the relative price structure shifts since World War II. Most of these changes are purposeful and relate to agricultural policies across the globe 6, 79
Food system changes
In the past 10 to 15 years, several factors have influenced the food supply of each country. The food system characterizing most urban and an increasing proportion of rural areas across low- and middle-income countries has changed drastically with globalized distribution of technology related to food production, transportation and marketing, mass media, and the flow of capital and services. Access to many new empty calorie foods and beverages relates to current economic and social development. Modern food technology has provided enormous benefits in reducing food waste, enhancing sanitation, and reducing many adverse effects of seasonality, among the myriad benefits. Similarly the same is true for the modern supermarket. Here we highlight some of the potential adverse effects of these important changes while acknowledging critical benefits to producers and consumers.
A key component is modern food distribution and sales. This reflects the enormous penetration of super- and mega-market companies throughout the developing world 80
. Most countries also have large convenience store chains. The fresh market (wet or open public market) is disappearing as the major source of food in the developing world. These markets are being replaced by large regional and local supermarkets, which are usually part of multinational chains (e.g., Carrefour or Walmart) or, in countries such as South Africa and China, by domestic chains that function and look like the global chains. Increasingly, hypermarkets (megastores) are the major force driving changing food expenditures in a country or a region. For example, in Latin America supermarkets’ share of all retail food sales increased from 15 percent in 1990 to 60 percent by 2000. In comparison, supermarkets accounted for 80 percent of retail food sales in the United States in 2000. This process is also occurring at varying rates in Asia, Eastern Europe, the Middle East, and all urban areas of Africa. We will undertake a national survey of diet and related factors in India in 2012.
One study suggests that the shifts in the food environment might enhance intake of processed, lower-quality foods81
. Carlos Monteiro has been particularly clear in his concern that this modern food environment has impacted diets 4, 5, 82
. Indeed his concern regarding processing meshes well with the vast shift away from consumption of legumes and coarse grains to consumption of refined grains purchased at modern supermarkets and convenience stores, which have penetrated urban Africa and Asia and most of the Middle East and Latin America.
The potential adverse effects of these trends are increased access to cheaper processed, high-fat, added-sugar, and salt-laden foods in developing countries. At the same time, they are the purveyors of some good. For example, supermarkets were instrumental in the development of ultra-heat treatment (UHT) for pasteurization of milk, giving it a long shelf life (not requiring refrigeration) and providing a safe source of milk for all income groups. Supermarkets were also key players in establishing food safety standards 83
. Most importantly, they solved the cold chain problem and in many instances have brought higher-quality produce to the urban consumer throughout the year. Other factors include the liberalization of direct foreign investment, trade liberalization, and the saturation of Western markets that has pushed growing companies into other locales. Improvements in the logistics and procurement systems used by supermarkets have allowed them to compete, on cost, with the more typical outlets in developing countries—the small mom-and-pop stores and wet markets (fresh or open public markets) for fruits, vegetables, and all other products.
Another result of the global changes in food consumption is the freer flow in food trade linked with the WTO. For instance, barriers to edible oil imports have been reduced, and vegetable oil production has been centralized to compete with imports and to significantly lower prices of vegetable oil in countries such as China.
These changes along with global investments in agriculture over the last half century have produced a large shift in relative prices to favor animal-source foods, edible oils, and other key global commodities, including sugar 79
. Supplemental Figure 3
, reproduced from research at the IFPRI, highlights some of the global trends that have resulted from the vast investment in the animal foods sector and feed crops across the globe 71, 79
. Supplemental Figure 4
highlights the real shifts in China in relative costs of selected foods based on data from 330 communities and their food markets 84
Food security and the dual burden of undernutrition and obesity
This rapid transition in income and diet and the large shift toward animal-source food consumption creates major demands for basic grains to feed livestock, disregarding the needs of the poor for the same food supply. While drought, climate change, and increased demand for ethanol have contributed to global food prices, the longer-term structural shift relates to demand for animal-source food and its impact on corn, rice, and wheat prices. In the face of the need for basic foods for the poor, the marketing, desirability, and availability of low-cost edible oils, empty calorie foods, and such have encouraged urban poor people to consume lower-quality foods that are obesogenic (most likely more processed foods, but this has not yet been documented). These complex changes are reflected in the emergence of obesity alongside hunger even in the same households.
Families faced with an inability to grow food or inadequate income to purchase food will likely opt for the cheapest cost per calorie from the available choices. When food prices for basic grains double or triple, the pressures to adjust food purchases increase. Among the most salient issues are the vulnerability of poor female-headed households 85
and the combination of price increases and volatility in global food markets (linked also with climate change issues). It is also important to note that the relative price changes matter most. If prices of fatty foods, oils, sugar, and animal-source foods go down relative to legumes, fruits, and other vegetables, the latter items become less attractive.
Despite substantial economic growth, large inequalities remain in many low- and middle-income countries, and it is common to see problems of underweight, stunting, and micronutrient deficiencies side by side with increasing rates of obesity. This “dual burden” of undernutrition and obesity exists not only in countries and communities 86
but in households 87, 88
and even in individuals, who may have excess adiposity along with micronutrient deficiencies, such as iron deficiency anemia 87–90
, or stunting and overweight. Dual burden households are most common in countries undergoing the nutrition transition 87, 88
and may reflect gender or generation differences in food allocation related to social norms. For example, high-quality foods may be given preferentially to adult males rather than to children. But other patterns may exist. In China it is common to indulge children in the wake of the one-child population control strategy 91, 92
. Individuals of different generations may also respond differently to social and economic changes, with the younger generation adopting new dietary patterns more quickly while the elderly continue to eat in more traditional (and sometimes healthier) ways.
A challenge for programs and policies is the need to address food insecurity and hunger without adding to the burden of overweight and obesity. This is particularly challenging given the relatively low cost and high availability of energy-dense but low-micronutrient-content foods. Again it is relative prices that matter. The lack of focus on coarse grains, legumes, and other vegetables and the vast attention to sugar crops, oilseeds, vegetable oil technologies, and cheaper animal-source foods have contributed to the global shift in diets.
In countries such as Mexico, Brazil, Chile, and China, where great strides have been made to minimize acute malnutrition through programs targeting vulnerable subpopulations, hunger and malnutrition have been reduced. An example is Oportunidades in Mexico, the conditional cash transfer program that provides a stipend and complementary food for preschoolers 93, 94
. These countries recognize that the programs must be tailored to address malnutrition while not accelerating energy imbalance and obesity among the recipients, as has occurred in some programs 93, 95
. For instance, Chile continued to feed young children in its various feeding programs even when most were adequately nourished and did not revise the programs to deal with energy imbalance issues for some time after they reduced undernutrition 95
. The Mexican government found a need to reduce the fat content of the milk along with other changes in its feeding programs to address problems of child obesity.