Trends towards overweight in lower- and middle-income countries: some causes and economic policy options

W. Bruce Traill^[13]

Abstract

Urbanization, globalization and economic development have led to dietary and lifestyle changes that encourage the consumption of high-value foods, including processed foods and food consumed outside the home. Together with reduced energy expenditure, this has resulted in growing problems associated with overweight in developing and, particularly, middle-income countries. One issue that has created interest but little analysis is the effect of changes in food supply chains that have been associated with globalization and urbanization - most notably the rapid diffusion of supermarkets in developing countries. There is little empirical evidence, but the increased availability of time-saving convenience products and the reduction brought about by supermarkets in the price of packaged groceries relative to fruit, vegetables and traditional staples would account for some of the switch to a higher energy density of the food consumed. The spread of such companies is an inevitable part of economic development and, rather than set up obstacles to their activities, it is sensible to develop policies that counter any harmful consequences of their presence. In developed countries, such policies generally try to respect individual freedom to make unhealthy as well as healthy choices (except possibly in the case of children), but also recognize that reducing health inequalities and influencing social norms are legitimate activities of government. A package of policy measures is necessary to achieve these objectives; such a package may include information, other communications, education, advertising restrictions, taxes on unhealthy foods or ingredients (commonly known as "fat taxes") and subsidies on healthy foods such as fruit and vegetables (sometimes referred to as "thin subsidies"). Good data and careful monitoring of outcomes are important because the existing base of evidence on the effectiveness of health care interventions to improve diets and health is poor, even in developed countries.

Introduction

The principal aim of this paper is briefly to present the evidence for the recent nutrition transition (towards overweight in developing countries) and dietary transition (changes in consumption of specific foods), paying particular attention to processed foods and looking at the extent to which these changes are linked to urbanization, globalization, changes in the supply chain and income growth. A second aim is to discuss policy options for countering overweight. Policy options for undernutrition and micronutrient deficiencies are not addressed in this paper as most countries already have measures in place to reduce these forms of malnutrition. Policy effectiveness draws on experience in developed countries with a view to learning what may lie in store for today’s middle-income and developing countries, and to suggest policy options for avoiding the harmful effects of the nutrition transition. Careful monitoring and data analysis must play an important role in informing policy

The received wisdom is that economic development, globalization and urbanization are bringing about a nutrition transition in which overnutrition joins undernutrition as a major problem facing developing countries. On the overnutrition side, the explanations -which are expressed clearly in Uustialo, Pietinen and Puska (2002), for example - include the following:

• Globalization leads to exposure to global mass media (linked to increasing TV ownership and viewing) and the heavy advertising of "Western" convenience and fast foods that are higher in sodium, sugar and fat (and generally more calorie-dense) and that are more highly refined than traditional foods.

• Urbanization leads to less strenuous forms of labour and (arguably) leisure, which reduces energy requirements.

• Urbanization leads to higher female labour force participation; the consequent higher opportunity cost of time results in a greater demand for convenience foods, convenient shopping and eating out.

• Technical change and openness to the global economy have made vegetable oils, meat and dairy products far cheaper than in the past, especially relative to incomes, so consumption of these products has grown at the expense of traditional staples, which tend to be more expensive in urban areas.

• Technical change and economies of scale in global food manufacturing and retailing, perhaps linked to global sourcing, make processed food cheaper than in the past and more readily available.

• Rising incomes, especially in urban areas, make overconsumption affordable.

• The increased population density associated with urbanization makes it possible to supply cheap foods for eating outside the home.

Overweight has become common in much of the developing world

Annex 1 shows under- and overweight incidence as calculated by Mendez and Popkin (2004) and the International Obesity Task Force. The following are some of the conclusions with respect to overweight:

• Overweight affects a substantial proportion of the population in almost all countries. Rates in Latin America, North Africa and European transition economies are approaching developed country levels.

• In general, overweight is a greater problem in urban areas, but in richer (and more urbanized) countries, the urban-rural distinction in proportion of overweight is relatively small.

• Generally, women are somewhat more overweight than men in low- and middle-income countries, but in developed countries the situation is reversed.

Overweight and income/socio-economic status

People derive pleasure from food and from their physical appearance and fitness/healthiness. Assuming that everyone has an "ideal" body weight - a weight that they would like to be for reasons of health and/or appearance, and that they would aspire to if it did not cost them anything to achieve in terms of money, effort or foregone pleasure from eating and drinking less than they would like - people whose weight is below their ideal would use some or all of any increase in income to eat more; for such people, weight increases with income and they derive extra utility both from eating and from being closer to their ideal weight. Weight will also be positively related to income for people who are heavier than their ideal weight, as long as the additional pleasure derived from being able to consume more food (and drink) exceeds the loss in utility from any extra weight they would gain. However, beyond some point, the losses in utility from gaining weight exceed the increases in utility from eating more, and the people affected are no longer prepared to spend more of their incomes on a greater quantity of food. In fact, there are good reasons to expect that as such people’s incomes continue to increase they will spend money to be less overweight if they can, by buying more expensive healthy foods, joining gyms, paying for membership of weight-loss groups, etc.

The relationship between income and weight is therefore predicted theoretically to be positive at first, then negative - although most people choose to be somewhat overweight. This relationship is strengthened at the population level if, as is generally accepted, income and education are positively related. In that case, better educated people are likely to have a lower ideal body weight than their less educated compatriots who are not as aware of the health risks of being overweight. The better educated population groups may also be better able to understand nutritional concepts of healthier eating.

The empirical evidence supports this theory. In developed countries, it is accepted that the incidence of overweight is greatest among disadvantaged groups, and this also seems to be the case in middle-income countries. Mendez and Popkin (2004) present evidence that in urban areas of highly urbanized countries, women of low socio-economic status (as measured by education) are more likely to be overweight than those of high socio-economic status, whereas the reverse is true in countries with low urbanization. It seems probable that urbanization in this context is really a proxy for income and socio-economic status (they are all highly correlated). Vio and Albala (2004) claim that in Chile the progressive increase in overweight and obesity is more prevalent in low socio-economic groups. Chopra (2004) reports that in the Western Cape of South Africa, 70 percent of women are overweight, but only about 20 percent perceive themselves as such. Whereas overweight is seen as a sign of wealth and status, most of these women associate underweight with illness, notably HIV/AIDS. However, younger and better educated women are aware of and aspire to the benefits of a slim body. In Brazil, obesity is positively associated with income in the poorer northeast of the country, but negatively associated with it in the richer southeast (Sawaya, Martins and Martins, 2004). Thus, this limited within-country data appear to support the view that as people develop economically and culturally (educationally) beyond a certain point, those with higher socio-economic status, especially the young, aspire to lower body weight, know how to achieve this and are able to modify their diets and lifestyles accordingly.^[14] This is also consistent with the findings of a recent cross-country analysis (Ezzati et al., 2005), which suggest that country-wide average BMI peaks for females at about US$12 500 (purchasing power parity [PPP]) and for males at US$17 000 (PPP), in each case thereafter declining as national income rises.

Knowledge of the relationships among income, overweight and consumption of specific foods is important for policy purposes. Certain demographic groups are particularly at risk, and the country-specific nature of these at-risk groups suggests the importance of monitoring both anthropometric and food intake data by income and demographic group. For example, a great deal of attention is paid to the rural-urban divide and the impact of urbanization on overweight and obesity. But if urbanization and income are highly correlated (and they are) studying single-variable relationships between overweight or food consumption in rural and urban areas may fail to uncover the main causes of malnutrition or to identify correctly the at-risk groups in the population. If the data allow, more sophisticated multivariate analysis should include other demographic variables such as education and age. Such detailed analysis of existing data would enlighten the policy process.

Overweight and the food supply chain

Extending slightly the theoretical model of the last section, it is recognized that people also derive pleasure from their leisure-time activities, and while occasional cooking might be a pleasure, for many people everyday cooking is similar to work and not a chosen leisure-time activity. Recent research in the United States (e.g., Philipson and Posner, 1999; Lakdawalla and Philipson, 2002; Cutler, Glaeser and Shapiro, 2003) suggests that technological change that makes available a huge supply of prepared foods (at affordable prices), which reduce enormously the time cost of food preparation, is a major contributor to obesity. In jointly optimizing their use of money and time, households consume more of these prepared foods at the expense of traditional time-intensive products. As both the time and money costs of food fall, people also consume more in total. Cutler, Glaeser and Shapiro (2003) give the potato chip (French fry) as an example. Previously these were laborious to prepare, requiring the peeling, cutting and deep-frying of potatoes, now they are available ready-prepared and frozen for easy final cooking in the oven or microwave (or fast food restaurant). Consumption has increased dramatically in the United States. While not all examples of technological change in manufacturing produce unhealthy foods (e.g., modified atmosphere-packed vegetables), in general prepared foods are more energy-dense and higher in saturated and trans fats, salt and sugar.

Cutler, Glaeser and Shapiro (2003) go on to show that in the United States declining exercise has had a relatively small impact on increasing overweight since the 1980s, mainly because structural adjustments in the United States economy had largely taken place by then; employment in agriculture or industry that requires physical labour was already at a low level and the move to the cities had largely taken place. Based on a detailed analysis of the United States Department of Agriculture’s (USDA) Continuing surveys of food intake by individuals, the authors’ explanation for the observed weight gain was a (small) increase in average calorie intake. Of particular interest, this increase in intake was not associated with larger portion sizes (which would have resulted in increased intake at lunches and dinners), more frequent eating out or female labour force participation, but with more frequent eating - i.e., snacking between meals. Preparing tasty snacks would traditionally have been highly labour-intensive, now it merely requires opening the cupboard or fridge. Thus, the simple availability of such products (at affordable prices) itself drives consumption.

Developing countries are still in transition from rural agriculture- and heavy industry-based economies towards urban, light industry- and service sector-based ones, so continued reductions in average energy use will occur and contribute to increasing problems associated with overweight. Nevertheless, the increasing availability of low-cost processed foods (including fast foods and soft drinks), which are generally more energy-dense and higher in salt, sugar and saturated and trans-fats than unprocessed alternatives, means that consumers will be likely to add such foods to their shopping baskets.

There is not a great deal of empirical evidence from developing countries, but the tendency towards consumption of snack foods is reported for urban India (Vepa, 2004), where there have also been rapid increases in consumption of biscuits, salted refreshments and prepared sweets (between 1987/1988 and 1999/2000 intakes of these products rose from close to zero to 68, 45 and 13 g per capita per day, respectively). Vepa suggests that processed foods, mainly driven by such snack products, may represent as much as 1 000 kcal in the daily diet of high-income consumers.^[15] Vepa’s data suggest an expenditure elasticity for processed foods in India of about 1.1, meaning that a 1 percent increase in income leads to a 1.1 percent increase in expenditure on processed food - this is high compared with most foods.^[16] A similar exercise for Lima, Peru, using data from a 2000 household survey as presented in Senauer and Goetz (2003), gives the following expenditure elasticities: food and drink away from home 1.13; candy and chocolate 1.10; prepared food consumed at home 0.55; and alcoholic beverages 1.09. As to be expected, given that Peru’s PPP income per head is more than US$5 000, which is almost twice India’s $2 670, the elasticity for prepared food is somewhat lower. Of interest with respect to Peru are the elasticities greater than 1 for food outside the home, confectionery and alcohol, all of which are calorie-dense.

As well as making available foods that consumers would not otherwise be able to obtain, supermarkets might also make a substantial impact on diets through their effect on relative food prices. The evidence suggests that supermarkets (and convenience stores) have reduced the prices of packaged foods but not fresh produce. Limited evidence from Brazil (quantitative) and elsewhere (anecdotal) suggests that supermarket prices for packaged foods are as much as 40 percent lower than prices in traditional outlets (Farina, 2002). By contrast, fresh fruit and vegetables are more expensive, and in general supermarkets offer less variety than traditional markets (thus fruit and vegetable’s share of the market is generally only half that of grocery products) while convenience stores often do not carry fresh fruit and vegetables at all.

As well as their natural advantage over small shops in selling cheaply processed, packaged and bulk foods such as edible oil, grains, noodles and condiments (Hu et al., 2004), supermarkets in China have moved very quickly in the past decade into processed semi-fresh foods such as tofu, dairy products and processed meats. Hu et al. (2004) argue that supermarkets have largely driven the rapid expansion in the milk products market.

In order to assess the dietary effects of changes in relative prices it would be necessary to obtain a complete matrix of own- and cross-price demand elasticities. In the absence of such a matrix, assume that packaged grocery prices fall by 20 percent owing to the existence of supermarkets, but other prices remain unchanged. If the price elasticity of demand for packaged groceries is -1 (a reasonable assumption for lower-income countries), consumption would rise by about 20 percent. It is harder to speculate on the quantitative impact on the consumption of other food products such as fresh fruit and vegetables, although the direction would unambiguously be down. Overall, the impact on diet quality is likely to be negative.

Changes in the food supply chain in developing countries

If supermarkets, food manufacturers and fast food outlets are to make cheap processed foods widely available to the public, they must have a substantial presence in a country.

The rapid expansion of supermarkets in developing countries has been most widely written about by Reardon and colleagues in a series of articles (e.g., Reardon and Berdegué, 2002; Reardon and Swinnen, 2004; Weatherspoon and Reardon, 2003; Reardon, Timmer and Berdegué, 2004). The line of argument is that supermarkets are no longer places where only rich people shop - over the past ten years or so, they have spread from the wealthy suburbs of major cities to poorer areas and smaller towns. This has happened in response to a number of forces, many of them interconnected: rising incomes (also associated with higher ownership of consumer durables such as refrigerators and cars, which facilitate supermarket shopping); urbanization; greater female participation in the labour force (increased opportunity cost of time); and the desire to emulate Western culture, spurred on by the globalization of media and advertising (linked in turn to the globalization of food manufacturers and the promotion of their products as well as of fast foods and soft drinks). There has also been a movement in most developing countries towards liberalization of trade and investment, which has brought the global supermarket chains on to the scene, along with economies of scale, buying power in purchasing and supply chain management skills.

The process of "supermarketization" began in Latin America in the early 1990s, and by 2000 supermarkets were delivering 50 to 60 percent of retail food sales in countries in the region (Reardon, Timmer and Berdegué, 2004). The take-off in Southeast Asia began between five and seven years later and is registering faster growth. A third wave has taken place in Eastern and Central Europe, while Africa is rapidly following, led by South Africa, which has seen a "spectacular" rise since 1994 (Reardon, Timmer and Berdegué 2004: 171). The process is also taking place in low-income Mediterranean countries such as Morocco and Tunisia (Codron et al., 2004). The implication is that this is an ongoing, even accelerating, process that will soon see supermarkets as the dominant food suppliers around the world. Projections to 2015 (see Traill, 2006) only partially support this view and suggest that, while income growth and urbanization will be contributing factors in the ongoing spread of supermarkets, the continued liberalization of foreign direct investment, resulting as it does in competition with and/or entry of multinational retailers, is likely to be the main driving force for the future spread of supermarkets in developing countries. However, even an open economy will not quickly bring high levels of market share to the low-income and highly rural economies of Southern Asia, and even in countries such as China the supermarket share of total food sales is not projected to rise above 30 percent by 2015 (although this is a substantial increase from the 2002 level of about 11 percent).^[17]

Nevertheless, it is clear that supermarkets are a fact of life, at least in urban areas, which implies that they will contribute to the nutrition transition by making available time-saving foods at lower prices, and these foods tend to be energy dense.

Globalization of food and soft drink manufacturing and fast foods, and their impacts on consumption

The spread of multinational food and soft drink manufacturers and fast food franchises has been well charted (see e.g., Bruinsma, 2003), but their impacts on food consumption have not been analysed. Conceptually, to the extent that they also increase availability and lower prices, they would also be expected to increase consumption. Wilkinson (2004) claims that United States investments in Mexico have concentrated on convenience and highly processed foods, especially snacks, beverages, instant coffee, mayonnaise and breakfast cereals. While it does not automatically follow that consumption of these products is higher than it would have been in the absence of multinational enterprises (MNEs), the controversy that reaches back at least as far as the debate about the ethics of Nestlé’s selling of powdered infant formula milk in developing countries from the 1960s is set to continue rumbling. Some figures in Annex 2 suggest that there has certainly been a very sharp increase in imports (and therefore, presumably, availability) of processed food products in the case study countries.

Fast food chains such as McDonald’s and Domino’s and soft drink companies (Pepsi, Coke) have also been blamed for unhealthy eating in developing countries (and also of course in developed countries, e.g., the film Super-Size Me). Pingali (2004) charts the growth of McDonald’s from 951 stores in Asia and the Pacific in 1987 to 7 135 in 2002, and in Latin America from 99 to 887 over the same period. Hawkes (2002) has undertaken an extensive review of the marketing activities of leading soft drink and fast food companies in developing countries, concluding that their numerous techniques to target children and adolescents indicate their intention of changing soft drink and fast food consumption trends over the long term. However, of potentially far greater importance for diets are the domestic companies that have sprung up to imitate global brands at much lower prices, which therefore have much higher sales (Vepa, 2004). There is no quantitative information on the impact of these changes on nutrient intakes.

Gehlhar and Regmi (2005) obtained data from Euromonitor that show how soft drink sales are growing particularly rapidly in Southeast Asian countries such as the Philippines (12 percent per annum) and Indonesia (22 percent). The data they present give Mexico a per capita annual soft drink consumption of 342 litres, higher than the United States (313 litres), the United Kingdom (170 litres), South Africa and the Philippines (about 65 litres), China (17 litres) and India (3 litres). That looks like a lot of sugar in Mexico!

Overall, it is virtually impossible to gather evidence to prove, one way or another, the impact that various changes in food supply chains are having on diets. The industry would certainly argue that it is simply satisfying latent demand - which is doubtless true to a point - but logic and circumstantial evidence suggest that this is contributing to trends in overweight. In any case, the supply chain changes are inevitably associated with economic development, and the solution must be to develop policies that counter any negative side-effects rather than to hold back development more generally.

Conclusions on the transition

This has not been intended as a comprehensive review of how diets have changed as countries have become richer - Schmidhuber and Shetty (2006), for example, have already done this thoroughly with respect to total energy, saturated fats and fruit and vegetables. The attempt here has been to focus on two causal issues of importance with respect to overweight: incomes and changes in the supply chain.

Of the many conclusions that might be taken from this review, one is that although growing quantities of data exist from household surveys, these have not been collected or analysed in a way that informs knowledge of what foods people actually eat and how this varies by population sub-group. For example, although it is informative to know whether people eat more or less dairy products or fruit in urban and rural environments, it would also be useful in the context of the obesity debate to know what types of processed foods they are eating, particularly snack foods. Greater knowledge about specific sub-groups of the population, for example the extent to which urban and rural consumption patterns can be explained by income and demographic differences between urban and rural populations, would allow a better assessment of the importance of any residual "urbanization effect" and of whether this is narrowing over time. In this way a country-specific evidence base for informed policy-making can be developed.

Policy alternatives: lessons from developed countries?

Overweight and obesity result from an imbalance between energy input and output, and in principle can be regulated by reducing input or increasing output. A public health policy must inevitably tackle both sides of this equation, but the following sections focus only on the input side, restricting discussion to interventions in food markets.

Virtually all of the literature and evidence on policy measures cited in this section relate to developed countries. It is assumed that the issues emerging in the middle-income and developing countries will mirror the developed countries, although it is recognized that the priorities for policy action will be different and the institutions for some policy interventions and enforcement may be absent in many less developed countries.

Economic justification for government intervention

A usual justification for governments to intervene in markets is the existence of some form of market failure; in the absence of market failure, it is argued, liberal democracies should allow their citizens to make their own choices about how best to lead their lives, even if the choices they make are risky ones such as mountaineering, riding a bicycle through city traffic or eating too much. Another common reason for intervention is the reduction of health inequalities among social groups.

In relation to overweight, three types of market failure have been discussed in the economic literature: the social costs of overweight may exceed the private costs; there may be uncertainty and/or asymmetry in the available information; and some individuals may not act rationally because they lack self-control.

In middle- and high-income countries, society has already decided that there should be some form of safety net so that individuals who become unwell do not have to pay the full cost of medical treatment - i.e., there is a national health service or State-paid compulsory health insurance for the poor. Similarly, days missed from work because of ill health are communally paid for (through social service systems or requirements on employers to comply with labour laws). Thus, when people take risks such as overeating, others in society bear at least some of the costs (social costs therefore exceed private costs), and society may feel that government, on its behalf, should take action to limit these costs. In circumstances similar to these, many countries have already acted with respect to smoking in public places^[18] and wearing seat belts and crash helmets - actions that were controversial when introduced because they were seen as intrusions on liberty, but over time have come to be widely accepted.

Uncertainty exists if a consumer is unable to make informed dietary choices, which may be because of inadequate nutritional knowledge or because too little information is provided on the nutritional content of food. The former may suggest a lack of nutritional education, but could also reflect the complexity and speed of change of nutritional knowledge. In the absence of information, even educated consumers are unable to make fully informed choices. The nutritional value of processed food in particular cannot be known accurately by the vast majority of consumers, who therefore find it difficult to regulate their intake from energy-dense foods of fats, sugar and salt. This is important when, for example, 75 percent of salt intake in the United Kingdom is from processed foods (Wanless, 2004).

Asymmetric information is a similar problem, occurring when one party in the market - almost invariably the seller - is better informed than the other, who is unable to judge quality by appearance. In the absence of regulation, the better informed partner therefore has an incentive to pass off low-quality (unsafe or unhealthy) produce to the more poorly informed.

Lack of self-control has a specific and technical definition within the economics profession, but essentially it means that with respect to certain decisions (such as whether to have another drink or piece of chocolate), some people discount the future to such an extent that they make choices that are inconsistent with their true time preferences; doing so reduces their overall welfare (O’Donohue and Rabin, 1999). It would be contentious to argue that governments should intervene because individuals lack self-control, but the principle is widely accepted that intervention is justified when someone could be made better-off without anyone else being made worse-off, which in theory is the case here.

Children

Children are often seen as a special case when the right of an individual to choose an unhealthy lifestyle is questioned. Children are deemed unready to make a whole range of personal choices, from marriage, to voting, to education, so it is not surprising that governments feel justified in acting to influence children’s diets, even if interventions have so far been very limited. Apart from questioning whether children should be permitted to make unhealthy choices even if they are informed, children generally have less knowledge and self-control than adults, and those who influence their behaviour (in determining their social norms) may not always be considered ideal role models (by adults).

Intervention may be justified both as a means of reducing the incidence of childhood overweight and obesity itself, and also by the theory that habits developed in childhood are carried forward into adulthood - overweight children usually become overweight adults.

Types of policy intervention

If the sole purpose of policy intervention is to make those who impose costs on society pay for them ("internalize the externality" as economists would put it), the best policy option is theoretically straightforward - a tax should be imposed on overweight people, in proportion to their degree of overweight and their consequent likelihood of imposing medical and other costs on society (this is the equivalent of the "polluter pays" principle). Of course this is impractical and ethically unacceptable given that it would imply taxing people with a genetic disposition to obesity. The tax would also be regressive, both because it would represent a higher share of the incomes of poorer people and because a larger proportion of poor than rich people are overweight, at least in developed and middle-income countries. In addition, in rich countries and among wealthier groups in poorer countries, where food is a small proportion of total expenditure and consumption is fairly unresponsive to price, it is unlikely that the tax would have much impact on obesity.

If the policy objective is to reduce overweight and obesity for reasons other than social cost, there are many practical opportunities to influence what people eat. In Table 1 these have been grouped according to the main objective of the intervention.

TABLE 1
Nutrition policy instruments classified by type of intervention

Source: Adapted from Mazzocchi and Traill, 2006.

Non-market interventions

Ideally people would choose to consume a healthy diet, and the first two and last sets of policy instruments in Table 1 have this goal in mind - make sure that foods are available that enable a healthy diet to be chosen, educate and inform people about what a healthy diet entails (at the same time countering unhealthy messages and claims from industrial advertisers), and provide sufficient information so that healthy options can be selected. When successful, these policies contribute to reducing the social costs of overweight and obesity, and when directed to disadvantaged groups they can reduce health inequalities and influence social norms in such a way as to make healthy eating accepted behaviour.

Informing consumers of the nutritional content of food (nutritional labelling) has been the least controversial policy measure in developed countries, although even this has not been easy to implement. In most countries, nutritional labelling of processed food is voluntary (the United States is an exception, and the European Union [EU] is planning to make nutritional labelling compulsory); where labelling is voluntary, regulation often specifies the form it should take when used. Unsurprisingly, this has resulted in multiple formats internationally, despite the best efforts of Codex (which has established guidelines). Nutritional labelling of processed foods imposes costs on businesses (administration, testing, design and print of labels), especially when exporting to a range of countries with different requirements, but Golan, Kuchler and Mitchell (2000) estimate that the social benefits outweigh the costs in the United States; their research concludes that consumers read labels and alter their purchase decisions. Producers also respond by introducing new healthier formulations such as low-fat foods. On the negative side, these authors calculate that nutritional labelling has had a minimal impact on obesity in the years since it was introduced (1991). Labelling of unprocessed foods and meals taken outside the home (including takeaways) has proved much more difficult, and it appears that no country has yet introduced such requirements. It is unlikely that such labelling would pass a cost-benefit test.

The other pillar supporting the informed choice edifice is nutritional knowledge. Nutritional education has re-emerged as a necessary part of the school curriculum, and information campaigns promoting a healthy eating message have been publicly funded in many countries, particularly those promoting fruit and vegetable consumption. Observers have noted that commercial advertising expenditure is concentrated on the "big five" of pre-sugared breakfast cereals, soft drinks, confectionery, savoury snacks and fast food (e.g., Miller, Skinner and Bryant, 2006), none of which would feature strongly in many healthy eating campaigns. Some have deduced that governments need to counter this flood of "harmful" information with more "good" information, but it does not necessarily follow that people’s choices among food groups would be affected by more balanced information. As Kuchler et al. (2005) state, again in an American context, "the sheer volume of media coverage devoted to diet and weight makes it difficult to believe that Americans are unaware of the relationship between a healthful diet and obesity". They quote surveys that show most American consumers to be aware of health problems associated with certain nutrients and able to discriminate among foods on the basis of fat, fibre and cholesterol. Adults in most middle- and high-income countries are all likely to have the same knowledge, although a case could be made for public service broadcasting to promote new knowledge as it emerges. The case of children however is the one that concerns most professionals. A major systematic review undertaken for the United Kingdom Food Standards Agency (Hastings et al., 2003) concludes that advertising to children affects the categories of food eaten as well as brand choice.

Some countries, such as Sweden, Denmark and Finland, have introduced controls on advertising to children, others are looking to manufacturers to introduce a voluntary code, and this seems to be an area where there is widespread agreement that some action is desirable.^[19] There is also a potential role for government policy in taking measures that affect what food is available to consumers. This is accepted with respect to some forms of food fortification, as well as the establishment of food safety and quality regulations to ensure minimum standards for food consumed. So far, however, standards have not been used to control the macronutrient content of foods offered for sale to the general public. However, governments have intervened to affect food availability in other ways, such as offering milk and fruit to schoolchildren and, in some American states (e.g., Texas), controlling the sale of soft drinks to children through vending machines. Collins and McCarthy (2006) show that the ease with which schoolchildren can obtain soft drinks, confectionery and salted snacks in schools is a major factor determining their overall consumption levels. This is consistent with the analysis of Cutler, Glaeser and Shapiro (2003), which emphasizes ease of access (time saving) as a determinant in the increased consumption of snack foods.

Governments are also beginning to take seriously their ability to influence diets through controlling the composition of meals in schools and other government institutions such as hospitals, prisons and public sector cafeterias. They may also act to regulate the salt, sugar, saturated and trans fatty acid contents of processed food that consumers cannot tell from the food’s appearance or taste - many consumers may be unprepared to read or unable to interpret labels. Rather that compulsory regulation, policy-makers in some countries such as Finland have entered into dialogue with industry, which has voluntarily reduced the levels of "harmful" nutrients

On the supply side there have also been calls in some quarters for more attention to be paid to access to healthy food (mainly fruit and vegetables) by disadvantaged groups who live in "food deserts" devoid of traditional local shops and who are unable to reach out-of-town supermarkets unless they own cars. The evidence that this is the case is far from compelling (White et al., 2004). Concern is also often expressed that healthy food is too expensive for the poor and that fats and sugars are the cheapest source of calories, so poor people consume a lot of them (e.g., Kennedy, 2005). This is sometimes presented as an industry conspiracy, calling for government control. The notion that healthy food costs more is usually based on a direct comparison between the prices of a regular product (e.g., mayonnaise) and its healthier derivative (low-fat mayonnaise), or between the prices per calorie of, say, asparagus and butter. In fact, it is quite possible to eat a diet that meets all health recommendations at very low cost (Henson, 1991), but doing so is time-consuming as it requires preparation from raw ingredients rather than buying time-saving prepared food.

Market measures

There has been increasing discussion in developed countries about the desirability of taxing unhealthy foods and/or nutrients - often referred to as "fat taxes". The issues are similar for middle-income countries. The idea is to increase the price of unhealthy foods relative to healthy foods or ingredients, thereby encouraging consumers to switch to healthy alternatives. However the pitfalls are also well known: the tax would be ineffective because the demand for foods is price-inelastic - there would be limited response to anything other than a very high level of tax; it would be regressive, hitting the poorest consumers hardest; and it would be unfair because slim people would also have to pay it (see e.g., Schmidhuber, 2004, Kuchler, Tegene and Harris, 2004). The tax might be more effective in developing countries, where consumers are more responsive to price, but it would ethically be very difficult to recommend a policy that taxed the poor and undernourished at the same rate as it taxed the rich and overnourished. The obverse of a fat tax has been called a "thin subsidy" (e.g., Cash, Sunding and Zilberman, 2006), which is a subsidy to encourage the consumption of fruit and vegetables. The authors find that demand for fruit and vegetables in the United States is quite responsive to price and that the cost of a statistical life saved by such a subsidy would be in the order of US$1.3 million, well below the typical benchmark figure used in United States government programmes of about $10 million. Nevertheless, for a cash-strapped government the total cost would still be substantial and would be subject to the charge that wealthy consumers also were having their food subsidized. Although this is true, it is also the case that poorer consumers would be the major health beneficiaries because their consumption is more responsive to price and they have lower fruit and vegetable consumption to start with, at least in urban areas. It is not unreasonable to contemplate a package whereby the money raised by a fat tax (e.g., on salty snacks, soft drinks and confectionery) was used to finance a thin subsidy.

The middle-income and developing country context

As already indicated, this review of nutrition policies and assessment of their effectiveness has been based almost entirely on developed countries. To what extent is it relevant to developing or middle-income countries, and how high a priority should anti-obesity policies be? Obesity has already become a problem in many developing countries and is set to become a much larger problem (Schmidhuber and Shetty, 2006). The social-private cost divergence may be less of a justification for action because few developing countries operate a health care system based on free access, nor do they have employment law that protects employees who are absent because of ill health. This means that the costs of obesity are largely borne by the individuals concerned and their families. Imperfect and asymmetric information, lack of self-control, changing social norms and reducing health inequalities remain reasons for policy action, and in this context it can be argued that policy should be a priority long before a problem arises; for example, it would be much better to influence social norms so that being overweight was never viewed as something to aspire to, rather than waiting until it becomes a health problem - although in many cases this has already happened, particularly where AIDS is prominent.

Concerning specific policies, it is probable that levels of nutrition education are lower in developing countries and it would be relatively cheap to introduce nutrition education into school curricula, at least in middle-income countries.^[20] The Republic of Korea and Malaysia have done this. Public information campaigns should be feasible, although they may not be seen as a first priority for the use of scarce public finances. Control of advertising to children would however be cheap and likely effective. Nutritional labelling is highly desirable in principle, but given that proportionately far fewer packaged groceries are sold in developing than in developed countries and that the enforcement of existing labelling legislation is often patchy, this may not be a priority. Measures to control the availability of snack foods and soft drinks for children in schools would be feasible and cheap, although some schools may be tempted to use vending machines as money raisers. Taxes and subsidies would be feasible in principle, but in practice are likely to be expensive to operate.

A package of measures

It is currently fashionable to state that policy-making should be "evidence-based", but with respect to diet and obesity, as indeed with respect to much policy-making in the area of public health, evidence is sadly lacking, even in the developed world. One reason for the difficulty in obtaining evidence is that changing diets is only one aspect of public health policy to reduce the incidence of non-communicable diseases (NCDs), alongside the promotion of exercise and reducing smoking and drinking. Advances in medicine may sometimes provide a substitute for dietary change (e.g., control of hypertension). A comprehensive, integrated and long-term package of policy measures may also work in synergy to provide benefits that cannot be identified with respect to individual policies in the short term. The famous Finnish North Karelia project adopted such an approach, and its achievements in terms of reduced coronary heart disease (CHD) deaths have been widely acclaimed. However, since the project was introduced and later extended countrywide, the incidence of overweight in Finland has steadily increased (Puska, 2002).

A report on encouraging behavioural change for sustainable development (United Kingdom Department of the Environment, Food and Rural Affairs, 2004) develops the "four Es of a new approach". Measures relating to enabling change include many of the educational and availability policies mentioned in Table 1. The object is to make it easy for people to change their behaviour, if they want to, by making sure that healthy foods are available and that people know what comprises a healthy diet. Engagement is about involving people in a policy so that they feel they own it and believe in its objectives; it is much more than telling people what they should do and needs to be long-term and consultative and to involve key nodes in social communication networks. Encouragement involves giving the right signals, which may include a combination of taxes and subsidies, as discussed earlier. Exemplifying means government leading by example, which may involve ensuring that its own mass catering provides healthy foods (and facilities for exercise), as well as taking care that its policies are consistent across the multitude of departments whose work impinges on obesity, as is increasingly recognized, for example by the World Health Programme (WHO) in its global strategy (WHO, 2004).

Conclusions on policy measures

Even for developed countries, there is an absence of strong evidence for what works and what does not at the individual policy instrument level, let alone for the effectiveness of a package of measures. For developing countries with limited resources for public health, it is especially important that: 1) interventions are directed to serious problems, which requires good data and proper analysis to assess where the problems lie; and 2) the effectiveness of any policy intervention is carefully monitored, ideally against realistic targets. Although there are lessons to be learned from experiences in other countries, many problems are country-specific and the way people react to policy measures is culture-specific. Once again this puts great emphasis on the collection of good data, and their careful analysis.

Overall summary and conclusions

Overweight and obesity are already common in middle-income countries and are becoming prevalent among some groups in less developed countries. Over the medium to long time horizon, the problems associated with overweight and obesity will become serious public health issues, and actions to tackle them should be taken sooner rather than later.

The reasons for overweight are many, not least economic development and the increasing availability of low-cost, time-saving alternatives to home food preparation. Although household surveys routinely collect information on the foods that people actually consume, these tend to be converted back into raw-product equivalents before analysis - dairy products, meat, cereals, etc., rather than cornflakes, carbonated soft drinks and potato chips. However, if these and other calorie-dense prepared foods are what people are increasingly eating and getting fat on, the existing data need to be analysed and new data collected with this in mind.

There are many possible policy interventions that might bring about dietary change, and a package of measures as part of an overall public health policy is most likely to be effective, especially when it comes to long-term change in social norms. Of course, policy-making should be evidence-based, but there is very little hard evidence on policy effectiveness, even in developed countries. At a minimum, well-targeted policy interventions require knowledge of which groups are most at risk. Children are one such group in all countries, but in many other respects problems are likely to depend on the stage of economic development and to be culture-specific. Identifying at-risk groups and their characteristics is another important task for data analysts. Which socio-economic groups are overweight? what are they eating? and how is this changing over time? are fundamental questions.

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Annexes

ANNEX 1: OVER- AND UNDERWEIGHT PROPORTIONS OF THE POPULATION BY COUNTRY

Overweight = BMI > 25
Underweight = BMI < 18.5.

ANNEX 2: PROCESSED FOOD IMPORTS: CASE STUDY COUNTRIES

The following figures support the view that dramatic increases have taken place in processed food imports in the case study countries; these changes will have led to large increases in availability. FAOSTAT trade data include a number of product categories that are candidates for having a high value-added content. The following products were selected from FAOSTAT as representing high added-value through further processing of agricultural raw material: pastry, breakfast cereals, beer, infant food, mixes and doughs, food preparations, flour and malt extract, frozen potatoes, sugar confectionery, olive oil, tomato juice (single strength), tomato paste, canned mushrooms, frozen vegetables, orange juice (single strength), wine, alcoholic distilled beverages, chocolate, fresh cream, butter, yoghurt, cheese, bacon, sausages, canned chicken, margarine, other prepared food. Although the presence of some items on this list may be disputed, it was applied uniformly across all countries. The figures show products that had the highest import levels at the end of the data period.