Food choice, energy balance and its determinants: Views of human behaviour in economics and psychology

Trends in Food Science & Technology 28 (2012) 132e142

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Food choice, energy balance and its determinants: Views of human behaviour in economics and psychology K.G. Grunerta,*, R. Shepherdb, W.B. Traillc and B. Woldd a

Aarhus University, MAPP Centre for Research on Customer Relations in the Food Sector, Haslegaardsvej 10, 8210 Aarhus, Denmark b University of Surrey, Department of Psychology, Guildford, Surrey GU2 7XH, UK c University of Reading, Department of Food Economics and Marketing, P.O.Box 237, Reading RG6 6AR, UK d Research Centre for Health Promotion, Faculty of Psychology, University of Bergen, P.O. Box 7807, 5020 Bergen, Norway

This paper shows how economic and psychological approaches to explaining why people overeat are based on different basic assumptions about human behaviour. Three such views of human behaviour are distinguished: rational behaviour, reasoned behaviour, and automatic behaviour. Economic approaches, trying to explain behaviour leading to weight gain and obesity based on the assumption of rational utilitymaximising behaviour, are contrasted with psychological

* Corresponding author. ILSI Europe, Avenue E. Mounier 83, Box 6, B1200 Brussels, Belgium. Tel.: þ32 2 771 00 14; fax: þ32 2 762 00 44. e-mail: [email protected]

approaches built on the softer assumption of reasoned behaviour and the more drastic assumption that major parts of especially eating behaviour are subject to automatic reactions to environmental stimuli. It is concluded that only the three approaches taken together can give sufficient insight into the various mechanisms determining food intake and physical activity, and that such a broad view is necessary for understanding the ways in which commonly advocated policy instruments can affect energy-related behaviour.

Why do people eat too much? Why do people eat too much and exercise too little? For all we know, it is not good for your health. It also results in that your looks do not quite match the current beauty ideal. So why do people still do it? Are they the victims of unconscious temptations that they are not even aware of? Are they just fighting to strike some kind of balance between leading a healthy life, enjoying the food they like, keep the family happy, and still have time for other things in life? Or are people making a rational decision that the immediate gratification of tasty food outweighs the possible risks of heart and other diseases twenty years from now? The answer to all three questions is yes. Yes, people are influenced in their eating behaviour by the mere presence of food in the environment and by food-related symbols to which they are exposed, and they are often not aware of these influences. People eat more when food is presented to them in bigger containers, or when tasty sweets are freely available and visibly presented. Yes, people make trade-offs when choosing food, and healthiness and energy content is often not the primary criterion. People choose the fat instead of the light cheese because they think it tastes better, the meat instead of the fish because the family does not like fish, and the pizza over the salad when eating out because they do not want to appear as a bore. And yes, people act rationally when choosing food. They buy more of a food when it gets relatively cheaper, they go for more convenience food when time gets more scarce, and they give less weight to the healthiness criterion when they are young than when they are old, because the negative consequences of unhealthy eating are farther away timewise, and hence will be discounted more.

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So all three mechanisms exist. But often we do not get the whole picture. The reason is that they are analysed in different branches of the social sciences and therefore not usually invoked simultaneously in any one study or publication. Rational human behaviour is the domain of economics e economists assume, as a point of departure, that humans act rationally, look at the implications of this assumption, and then collect data to see whether these implications hold in real life. Decision-making involving trade-offs and conflicts is analysed in social psychology. Unconscious effects of environmental stimuli on our behaviour are also analysed in psychology, but in a different branch where one deals with automatic or habitual behaviours, not the reasoned ones where one tries to reconcile different criteria. In the public policy debates on how to address obesity and other aspects of unhealthy eating, we usually do not get the whole picture either. Decision-makers in public policy have their own views on what drives human behaviour in the domain of food and physical activity. These views may be inspired by the literature on determinants of food choice and physical activity, but rarely encompass all three views mentioned above. It is the aim of this paper to present and contrast the three different views on determinants of (un)healthy eating that we find in the social science literature: rational behaviour, reasoned behaviour, and automatic behaviour. We will present the major assumptions guiding these three views, briefly present major theories that build on these assumptions, and give examples of empirical evidence supporting them. The major message that we want to get across is that these three views, although conflicting in their assumptions on human behaviour, are all supported by considerable streams of research, with huge bodies of empirical evidence. If we want to get a comprehensive view of why people eat too much, we thus need to take into account all three views. This also implies that any enlightened public policy that addresses the issues of obesity and other forms of unhealthy eating should consider all three mechanisms. As we will show at the end of the paper, most instruments currently promoted to address these issues implicitly assume one of the three mechanisms. Four limitations of this paper should be addressed right away. First, this paper will not provide a review of all the empirical evidence supporting the three views, which would be far beyond the scope of a journal article. Our focus is on the principles of human behaviour on which the three views build, their complementarity, and their implications for understanding the obesity issue and how to deal with it. Second, we will not deal with physiological determinants of behaviour, like the impact of physiological homeostasis. Third, there are other approaches to explaining food choice beyond the three addressed here. We believe that the three approaches presented here cover the bulk of what has been done in economics and psychology, which in turn are those branches of the social sciences that have

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done most work on determinants of food choice and, to a lesser extent, physical activity. However, other relevant work has been done in areas like sociology (e.g., Beardsworth & Keil, 1997) and anthropology (e.g., Mintz & Du Bois, 2002). This will not be covered. Finally, we deal with human behaviour on the demand side only, i.e., we only look at the behaviour of people eating and exercising. One could also apply principles of human behaviour to an analysis of behaviour on the supply side e what are the factors leading the food industry to produce the foods that they bring on the market, what are the factors leading decision-makers in public and other bodies to make decisions making it easier or difficult for us to engage in physical activity in our daily life. View 1: rational behaviour Rational behaviour is the domain of economics. In economic theory, it is assumed that people act rationally (see, e.g., Arrow, 1986). Traditional (neo-classical) economics begins with the principle of consumer sovereigntyd informed consumers are free to make their own decisions about what to buy and are better able to weigh up alternatives and choose combinations of products that satisfy their unique preferences than any outsider. In deciding on their overall diets, people make decisions that maximise their utility (or satisfaction or happiness). They derive utility from all sorts of goods and services, but their resources to buy them are finite, so they must make choices constrained by their incomes and the prices of goods and services. This basic economic model has been extended in several ways. First, it has been recognized that food consumption decisions affect consumer satisfaction both directly (e.g., pleasure from eating and drinking) and indirectly (e.g. potential frustration from obesity, dentists’ bills, adverse health consequences). Economists believe that an informed person takes her consumption decisions after balancing the pros and cons, including possible health implications. Second, it has been recognised that time as well as income is a constraint. Competition for limited household time constrains the degree of food preparation and exercise people are willing to undertake (Becker, Maiman, Kirscht, Don, & Drachman, 1977). Third, foregoing the immediate pleasure of eating, or suffering (for some) the immediate displeasure of cooking or exercising must be balanced against possible health benefits a long time in the future, so these decisions also depend upon time preferences how much people are prepared to forsake present consumption in favour of future consumption (what economists call their time preference or discount rate). And while the immediate outcomes may occur with some certainty, the long-term consequences are often not only far out in the future, but also less certain. The more complete the model, the more apparent it becomes that almost all variables are ‘endogenous’ - decisions about health, incomes, the amount of leisure and the amount of exercise people take as well as

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the amount and types of food they eat and their weight are all taken jointly. Economics assumes that consumers are well informed about products and about the health consequences of their actions. However, economic theory acknowledges that information can be imperfect. If consumers under- or overestimate risks due to imperfect information, the impact of education or better information is, from the economic perspective, ambiguous: if it leads most people to increase their perceptions of the riskiness of obesity they would respond by eating less and exercising more, but if it leads most people to reduce their perceptions of the risks of obesity, they would eat more and exercise less; given the huge, often alarmist, media and policy attention the subject has received it is by no means self-evident that the risks of overeating are presently underestimated. Based on the assumptions made in economic theory, it is possible to derive predictions on how people’s behaviour will change in response to changes in parameters like prices (both absolute and relative), income, available time, and available information. In addition to predicting change ( positive economics), economic theory can also be the basis for judgements about the impact of economic organisation and policy intervention on welfare (normative economics). A main implication from economic theory in this respect is that competitive markets comprising informed consumers and producers acting in their own self-interest are socially optimal (Adam Smith’s ‘invisible hand’, meaning that an invisible force coordinates activities to the common best). When markets ‘fail’, policy intervention may improve welfare. Classic examples of market failure are those involving externalities, e.g., cases where behaving in a certain way imposes costs on others. If, for example, overeating imposes health costs on the society at large, then normative economics would call for measures where those costs are allocated to those causing them (i.e., those who eat too much) or for measures reducing the incidence of the behaviour causing those costs, i.e., measures that reduce overeating. Is there empirical evidence that supports the view that increases in obesity can be explained by people’s rational, utility-maximising behaviour? The price of agricultural and processed food products has been falling in real terms (relative to other products) by some 20% since 1980, mainly due to technological change in food production, and with some obvious variation across countries and time, notably the 2008 price spike (Mazzocchi, Traill, & Shogren, 2009). Economic theory predicts that demand for a product goes up when its (relative) price falls. Empirical analysis shows that in developed countries the responsiveness of calories to price is low, with an elasticity of around 0.1 (Seale, Regmi, & Bernstein, 2003), so a 20% fall in price might explain a 2% increase in calorie intake (all else constant). This amounts to around 40e50 calories per person per day. It would be higher in transition and developing economies

where demand is more responsive to price. Poorer sections of society are also more responsive to price, so their demand would have increased faster. Income inequality has actually risen together with obesity rates, suggesting that the average price elasticity of calorie demand may have gone up. Technological change has also resulted in relative price changes within the food area, resulting in lower prices of processed foods relative to the price of fresh produce (Mazzocchi et al., 2009). Theory suggests this would lead people to consume a larger proportion of their food in processed form. It is sometimes claimed that processed food is usually more energy dense than homemade food, even though such comparisons are complicated by the fact that products may not be strictly comparable. To the extent this is true, and if people do not compensate by eating smaller portions, this would lead people to consume more calories. There is no empirical evidence on the extent to which the switch over time to processed foods is priceled (rather than convenience led), but people are known to be responsive to relative price changes of close substitutes. As a result of technological change a plethora of affordable convenience foods and fast foods have been developed; these offer consumers the opportunity to reduce the time spent on food preparation. Cutler, Glaeser, and Shapiro (2003) present compelling evidence for the US (the only country with long time series data) that people now eat more often (snack more), essentially because snacking has become both cheap and easy. Real incomes have grown at around 2% per year since 1980, which could be another explanation of a raising demand for calories that is consistent with economic theory. But the demand for calories is not very responsive to income in developed countries, though again poorer people and countries are more responsive to income gains (Mazzocchi et al., 2009). The existence of a time-preference can explain why young people are less concerned about adverse health effects of over-eating than older people. For a 20 year old, the disutility from potentially becoming, say, a diabetic in 50 years time discounted at 3% per year is 23% (¼1/ (1.03)50) of the disutility from the same condition now. But for a 60 year old, the disutility would be 74% (¼1/ (1.03)10) of the disutility from the condition now. If health were the only concern, it would be rational for a young person to eat less healthily than an older person. In fact, we observe that young people do eat less fruit and vegetables and more snack foods than older people. For example, data from the UK National Diet & Nutrition Survey (Swan, 2004) show that the percentage of energy from nutrients like saturated fats and carbohydrates is higher for the group aged 19e24 and declines as age increases, while intakes of vitamins follow the opposite path. Similar results can be found in Italy, where the percentage of individuals who only consume one portion of fruit and vegetables per

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day or less is much higher in the youth age (about 21% between 18 and 34) and becomes smaller at older ages (16% between 45 and 54, 13% above 60). NHANES data for the US (Ervin, Wright, Wang, & Kennedy-Stephenson, 2004) confirms that teenagers consume almost twice as much saturated fat as those in the age bracket 40e59.1 Compared to studies on energy intake by eating, energy expenditure in terms of physical activity has rarely been studied within an economic approach (Madore, 2007). According to Sturm (2004), decisions about level of physical activity should be divided into the domains of work, leisure and transportation. Sturm argues that work is the least interesting domain for explaining rises in obesity, because the major technological changes making paid work less energy intensive occurred long before the onset of the obesity epidemic. As for leisure, leisure industries associated with more sedentary lifestyles such as spectator sports, cable TV and DVDs have grown the fastest during the last 40 years. On the other hand, several studies indicate that leisure-time physical activity has increased over the last 30 years (Borodulin, Laatikainen, Juolevi, & Jousilahti, 2007; Samdal et al., 2007; Steffen et al., 2006; Sturm, 2004). Thus, declining leisure-time physical activity does not appear to be a cause of the obesity epidemic. Transportation may therefore be the most promising area to look for developments that have contributed to the rise in obesity. For example, data from the National Travel Survey show that in England between 1975 and 2002 the average number of miles per year travelled by foot fell by around a quarter and by cycle by around a third (Allender, Peto, Scarborough, Boxer, & Rayner, 2006). Over the same period the average number of miles per year travelled by car increased by just under 70%. With regard to the obesity epidemic, Sturm (2004) proposes that “the transportation area may offer the most promising interventions from an economical perspective: Transportation patterns depend to a large extent on public goods, and there are large externalities associated with individual mobile use”. Economic research on individual decisions about use of transportation with regard to walking or biking versus driving a car is still scarce. The economic approach tries to reconcile the assumption of human rationality with the fact that people are getting more obese. Under which circumstances is it rational to add body weight? The reasoning and results mentioned above give some answers to this: when the prices of food fall, especially of energy-dense convenient food, when the consequences of unhealthy eating become less serious due to medical progress, and when the pleasures of eating are immediate and the rewards for healthy eating are far ahead in the future, as well as when it is more convenient

1

This is not ‘proof’ that discounting is responsible for differential eating patterns, many other factors may have an influence and rigorous quantitative analysis should identify and control these factors.

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and time-saving to travel by car instead of walking or biking. The economic approach provides some contrast to much of the public discourse on obesity and the lifestyle factors leading to it, which is often characterised by an implicit assumption that it is people’s ignorance, stubbornness and thoughtlessness that leads them to eat more than they should or leads them to eat the wrong food, and much of the measures devised to reduce obesity therefore aim at enlightening, informing and educating people. However, when the behaviour in question can be shown to be compatible with rationality, the framing of the issue becomes broader. Obesity-inducing lifestyles can then also be viewed as an adaptation to external factors, preserving the overall goal of maximising utility. If, for some reason, one wants to decrease obesity, it would follow from this reasoning that the external conditions would have to be changed e for example, by changing food and gasoline prices, changing prices of medical care, subsidising sport and recreation activities, providing low energy food that in terms of the utility derived from food (like pleasure, satiety) is completely equivalent to existing alternatives, changing the availability of food, or changing the street designs or developing less sprawling urban contexts. One should add, though, that economists are aware of the fact that people may not be fully informed about the consequences of their behaviour, and that therefore providing additional information may indeed change their behaviours. This goes both for information about long-term consequences of unhealthy eating, of which some people may not be aware, and for information about product characteristics, which people would need to know in order to make informed rational decisions. Recently, the area of behavioural economics has attracted some attention also in the discussion on obesity. Behavioural economics is a hybrid of economics and psychology that acknowledges that people may not always act rationally, and borrows concepts from psychology to analyse deviations from economic rationality (see Kahneman & Tversky, 2000; Wilkinson, 2007). It has become popular in a policy-making context, not least because of Thaler and Sunstein’s concept of nudging (Thaler & Sunstein, 2008). Nudging is about influencing choices by the way choice options are framed and arranged, drawing on concepts from the two views of human behaviour presented in the following two sections. We will not deal with behavioural economics separately here, partly because it does not add a distinct view of human behaviour, partly because there are no empirical applications to our focus area. It is worth mentioning that not all apparent deviations from economic rationality should really be treated as such. Collecting and processing information is timeconsuming, so may be considered a transaction cost associated with any attempt to eat healthily. Rational consumers would balance these costs against expected benefits and in many cases decide not to read nutritional labels or lists

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of ingredients in food, preferring to stick to habitual behaviour. The outcome is what Simon (1982) refers to as satisficing behaviour and bounded rationality and can help explain why consumers are not more responsive, for example to new health information or reformulation of products. View 2: reasoned behaviour This and the following view of why people add weight are based on streams of research in psychology. Psychology is not in the same way as economics dominated by one major body of theory. Instead, psychology has developed many small and medium range theories. Some differ clearly in the aspects of human behaviour that they address, whereas others overlap considerably both in the type of phenomena they seek to explain and in the types of constructs used as predictors, so that differences between theories sometimes are mainly in terms of terminology and certain nuances. We can distinguish two main streams of literature here, with distinct contributions to the topic of energy balance and obesity: approaches analysing human behaviour as reasoned and guided by consciously formed intentions, and approaches looking at automatic (unconscious) reactions to environmental stimuli. We start with the view of human behaviour as reasoned. The common assumption here is that, before engaging in some behaviour like taking a snack, ordering a supersized portion, opting for the meat instead of the fish, or taking the car instead of the bicycle, people form an intention to perform this behaviour, which in turn is based on some form of conscious reasoning. There exist a large number of social psychological models that attempt to explain the reasoned formation of intentions and which have been applied to both food choice and physical activity. Many of these have common origins and there is considerable overlap between them. In terms of social psychological models the primary ones are the Theory of Reasoned Action (TRA) and its successor, the Theory of Planned Behaviour (TPB, Ajzen, 1991). Other models are Bandura’s Social Cognitive Theory (1997), the Health Belief Model (Becker et al., 1977) and Protection Motivation Theory (Rogers, 1975). Especially in research on physical activity, contemporary theories of motivation (e.g., Achievement Goal Frameworks, (Elliot & Dweck, 2005); Self Determination Theory, (Ryan & Deci, 2000)) and self-regulation have also been widely used. The common core in these theories is that the intention to perform a certain behaviour is determined by three groups of factors:  The expected outcomes e both positive and negative e of performing the behaviour  Norms and values governing this type of behaviour e these may be social or injunctive norms, where one perceives some pressure from the social environment to perform certain behaviours and not perform others, or personal or descriptive norms, which set standards for what kind of behaviours are regarded as good or bad.

Personal norms may develop based on modelling, i.e., taking others’ behaviour as a model for one’s own, a mechanism emphasized especially in Social Cognitive Theory.  Expectations on whether one will be able to actually perform the behaviour e where reasons for not being able to perform a behaviour include lack of resources, lack of skills, lack of backing from the environment, lack of trust in one’s own willpower. Compared to the economic approach, where people are expected to choose those behaviours that result in the highest utility for them, the reasoned behaviour approach provides some more specificity. The first group of factors, trading off expected positive and negative outcomes of the behaviour is very close to the economic utility maximization approach. As for the second, economists may argue that the effect of norms and values enters the utility function by increasing or diminishing the utility of a certain behaviour, depending on whether it is congruent or discongruent with norms and values, but here they are singled out as an additional group of determinants. The last group of determinants is usually not addressed by economists, but both social norms and environmental facilitation are part of the nudging concept (Thaler & Sunstein, 2008). There have been many studies on food choice using this general approach, attempting to explain behavioural intentions related to fat intake, fruit and vegetable consumption, and ‘healthy eating’ in general (Conner & Armitage, 2006). Likewise, there have been studies in the area of physical activity (Marshall & Biddle, 2001), and a few on overall energy intake (Armitage & Conner, 2001; Baranowski, Cullen, Nicklas, Thompson, & Baranowski, 2003). In general there is relatively good prediction of intention by the groups of factors mentioned above, with expected outcomes being the dominant predictor. However, when we look at the prediction of actual behaviour (and not just intention to perform the behaviour) the degree of prediction tends to be lower. While relatively clearly defined behaviours such as fruit and vegetable consumption are predicted reasonably well (32% of the variance in behaviours in a study employing the TPB, (Povey, Conner, Sparks, James, & Shepherd, 2000), for participation in physical activity and more global dietary behaviours such as fat intake the prediction of behaviour tends to be lower; for example Armitage and Conner (1999) found only 18% of the variance in fat intake (as measured by a food frequency questionnaire) to be accounted for by the TPB variables. One potential reason for this is perhaps that the number of ways of achieving a well defined goal such as fruit and vegetable consumption is limited whereas there are far more ways in which it is possible to achieve more diffuse goals such as a reduction of fat or energy intake (Conner & Armitage, 2006), or an increase in energy expenditure. Expected outcomes being the most important predictor, studies have also investigated the importance of specific

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outcome beliefs. For example, Towler and Shepherd (1992), investigating the influences on the consumption of chipped potatoes, found the two beliefs most related to intention were those related to taste and that the food was filling. Shepherd and Towler (1992) found that taste and perceived healthiness were the strongest predictors in relation to several types of foods contributing to fat intake. Armitage and Conner (2000) used the beliefs that differentiated between intenders and non-intenders to develop an intervention aimed at changing attitudes towards eating a low fat diet; this specifically targeted beliefs regarding the taste of low-fat food, influence on level of fitness, weight control, health, and enjoyment of food, and found this belief-based intervention to be more effective than a control intervention based on general information on low fat. Whereas expected outcomes of the behaviour emerge as the most important predictor when studying behaviour related to food choice, self-efficacy emerged as the most important predictor in studies attempting to explain intentions and behaviours with regard to physical activity. Perceived barriers like lack of confidence in one’s ability to be physically active on a regular basis, lack of time, too tiring, too weak, bad weather, no facilities and lack of exercise partners were shown to be significant correlates of intentions and behaviour with regard to physical activity (Sallis, Prochaska, & Taylor, 2000). Beliefs about the outcome of a behaviour can be a mix of positive and negative expected outcomes, reflecting a degree of ambivalence (Maio, Haddock, & Jarman, 2007). Ambivalence refers to holding both strong positive and strong negative beliefs simultaneously and this is likely to be common in many food contexts. Thus people both like the short-term sensory pleasure from consuming certain foods while simultaneously having negative beliefs and attitudes regarding their impact on long-term health. In a study on expected outcomes of eating more fruits and vegetables, a group of adolescents believed that this would result in more fitness and better looks, but also in ‘illusory satiety’ and in being regarded as ‘too healthy’, which was seen as socially undesirable (Kazbare, BechLarsen, & Grunert, 2010). Similarly, people may have negative experiences when engaged in physical activity (e.g. muscle pain, exhaustion) while simultaneously having positive beliefs and attitudes regarding its impact on long-term health. We have some parallels here to the trading-off of long-term and short term consequences of a behaviour in economics, as expressed by the discounting factor. Ambivalence has been shown to act as a moderator of the relationship between attitudes and intention and between attitudes and behaviour (Birch, 1980; Conner, Povey, Sparks, James, & Shepherd, 2003; Mark Conner et al., 2002). Those higher in ambivalence show less consistency between their attitudes and the behaviour and therefore might present more difficulties in terms of

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interventions targeted at changing particular beliefs, because it implies that even when an outcome belief e say, about a serious health consequence of certain eating habits e is changed as intended, this will not necessarily translate into changes in intentions and behaviour. Evidence thus suggests that ambivalence is an obstacle to adopting healthy behaviours consistently. A key problem in reaching individuals who are psychologically ambivalent is that they are more sceptical and will scrutinise information in order to make their position more comfortable giving rise to less internal conflict. Hence ambivalent individuals are more likely to find fault in health campaigns, particularly those that are simplistic (Maio et al., 2007). The reasoned behaviour view shares with the rational behaviour view the assumption that human beings are goal-oriented, i.e., that they have goals they want to pursue and that they evaluate alternative behaviours or choices by the extent they are believed to lead to outcomes that are regarded as desirable or undesirable in the light of those goals. However, while the rational behaviour view seeks to explain human behaviour by the unitary goal of maximizing utility, the reasoned behaviour view allows multiple goals, which may be inconsistent with each other and change over time. Also, compared to the analysis of rational behaviour in economics, it provides more insight into the processes leading people to choose one behaviour and not another, and it opens up for other levers to change behaviour. It softens the rational behaviour approach by acknowledging that goals can be inconsistent over time and with each other, and that situational factors determine which goals are salient in any given choice situation. Thus, pleasure may be more important than health when choosing cheeses for a dinner party, but not when choosing cheese for children’s lunch packs. It provides more insight into how people choose foods and behaviours related to energy intake by distinguishing different groups of factors affecting the reasoned formation of intentions, namely beliefs about outcomes, about norms, and about self-efficacy, and by also providing insight into the mechanisms by which these beliefs are formed by various forms of learning. It opens up for other levers of change in at least three ways. First, as for informational instruments, these can aim at informing on outcomes of certain food choices or of different kinds and levels of physical activity, but they can also aim at informing about social norms on eating and physical activity, or at educating people in such a way that they achieve the competence to make the ‘right’ choices, thereby increasing their self-efficacy. A second lever of change is to make health-related outcomes more salient at the time where people form intentions and implement behaviour, by providing reminders that will ‘prime’ these outcomes. A third one relates to measures that increase selfefficacy with regard to healthy choices, i.e., that make healthy choices easier to implement. Examples could be increased transparency about the nutritional properties of

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food, meal planning aids, and product reformulations that make products healthier. View 3: automatic behaviour The models described in the preceding section explain behaviour based on conscious thought about the pros and cons of the behaviour, about trust in your own ability (self-efficacy), and about values and norms. However, many frequently performed behaviours, like eating, drinking and moving about, do not involve a lot of conscious reasoning. Rather, people may act automatically, either because they have developed habits or because they react to external stimuli because of mechanisms that they are not even aware of (Bargh & Chartrand, 1999). Both forms of automatic behaviour can be found in the areas of food choice and physical activity. Habitual forms of behaviour have been dealt with in streams of research that are distinct from those described in the previous section. By definition, habit is a form of automaticity in responding, which develops as a person repeats a particular behaviour under stable circumstances (Verplanken & Aarts, 1999). Applying this to determinants of physical activity, Verplanken and Melkevik (2008) argue that a strong physical activity habit implies the fact that regular physical activity is self-evident, does not require thought or deliberation to initiate, and is incorporated as a part of a person’s daily or weekly activities. Such an approach implies a search for the characteristics of contexts and activities that may support the development of frequent and repeated physical activity in a structured environmental context. Recent work in physical activity research therefore also acknowledges the role played by the physical environment, and has led to the development of ecological approaches to the understanding of how physical activity is influenced by the interplay between individual characteristics and social and physical structures (Giles-Corti, Timperio, Bull, & Pikora, 2005; Trost, Owen, Buman, Sallis, & Brown, 2002). Past exercise behaviour or exercise habits emerged as consistent predictors of current physical activity status. Participation in organised youth sports has consistently been found to be associated with a higher level of adult physical activity (Telama, Yang, Hirvensal, & Raitakari, 2006; Trudeau, Laurencelle, & Shepherd, 2004). Habits can be the automation of decisions that at some previous point in time were made in a reasoned and conscious way. If somebody at one point has reasoned that a low-carb diet is good for you and starts implementing it, the behaviour may over time become automated and the original reasons for the decision may not even be remembered. As long as the person’s own condition and the characteristics of the environment don’t change, there may be no need to reconsider the behaviour. When the person’s condition or the environment change, however, the habit may become dysfunctional and may have unwanted consequences, like obesity.

Not all behaviours have been reasoned at some point in time. Behaviour can be experimental, like buying a food just to see how it tastes, and this behaviour may then become reinforced and gradually habitualized if it leads to gratification, like when the food has indeed a good taste. People may in this way acquire habits for behaviours where possible trade-offs between pleasure and health have never been considered. Habitual behaviour is, compared to rational and reasoned behaviour, more difficult to change by information, as there is no motivation to attend to and process such information. Even when information is attended and understood, people may not be interested in changing the habit, or may find implementing such changes too difficult. Other forms of automatic behaviours are not based on habits, but are simply responses to environmental stimuli governed by mechanisms people may not be aware of (Bargh, 1992). In the food area, automatic responses to environmental cues are addressed in approaches deriving from Schachter’s externality theory (1968), which suggests that the obese pay more attention to external cues in eating (e.g. the sight and smell of food) rather than internal cues of hunger and satiety used by normal weight individuals. Wansink (2006) argues that much of eating is not thought about in a careful way, and that the decisions people make regarding food are often ‘mindless’ (Wansink & Sobal, 2007). This can lead to overconsumption in cases where there is distraction or where the usual cues regulating consumption are not present. For example, most eating occurs in the presence of others. Research clearly indicates that a social facilitation effect leads to lower levels of food consumption when people eat alone and to higher levels when eating occurs in a group setting. Work by de Castro and de Castro (1989) has shown that the amount of food consumed increases with an increasing number of individuals present at a meal. This is true even when those eating alone are excluded from the analysis (Shepherd, 1999). Family and friends also provide a source of modelling and peer pressure for consuming particular foods, including higher-fat foods, and for trying new foods. Studies with focus on automatic reactions have mostly been carried out under laboratory conditions, since they usually require strict controls of other factors affecting the behaviour. This raises issues of external validity, and inconsistencies between controlled experiments and market data have indeed been pointed out. For example, the experimental finding that people eat more when presented with larger portion sizes (Wansink & Sobal, 2007) suggests that firms can exploit this, thereby encouraging overeating. However, data on actual food consumption behaviour (as recorded in household surveys) suggest that there has been no tendency for people to consume more calories per sitting, and that extra calories are rather consumed by eating between meals (snacking) (Cutler et al., 2003). Such inconsistencies underline the need for a problem-

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oriented approach to analysing causes of obesity that cut across the disciplinary boundaries in the social sciences. As noted, automatic behaviours are difficult to change by information. As they involve repeating the same behaviours in stable environments, or reacting unconsciously to stimuli in the environment, the most immediate lever for changing automatic behaviours are changes in the environment, a point that is also heavily emphasized in the nudging concept (Thaler & Sunstein, 2008). Examples of this are food availability, food composition, package and portion sizes, snacking opportunities, environments commanding physical activity. Three views of human behaviour: conflicting or complementary? We have, in the above, shown that economic and psychological approaches to the explanation of behaviours related to energy balance and obesity are based on three different views of human behaviour: human behaviour as rational, reasoned, and automatic. These three views can be placed on a continuum, with rational behaviour at one and automatic behaviour at the other end (Fig. 1). In the middle, we have reasoned behaviour (behavioural economics, which heavily borrows concepts from social psychology, would be placed there as well). The reasoned behaviour approach, as exemplified by the Theory of Planned Behaviour, shares with the rational behaviour approach in economics the basic assumption that people try to seek pleasure and avoid unpleasantness, and that behaviour has some degree of goal orientation. However, whereas neoclassical economics works with the single goal of maximizing utility, the reasoned behaviour approach allows a multiplicity of goals, acknowledges that such goals can be inconsistent and change, that information (or lack of it) therefore will affect behaviour not only by informing about consequences of behaviours, but also by making goals more or less salient, that people’s behaviour is affected by values and norms, and that people may not always be able to implement behaviours that they in principle find desirable. The automatic behaviour approach acknowledges that behaviour related to food and physical activity may not always be the result of conscious reasoning, may be habit-based, and may result from automatic reactions to environmental stimuli. Habitual behaviour is acknowledged both in economics (e.g., Dynan, 2000) and in research based on the reasoned behaviour approach

Fig. 1. Continuum of approaches.

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(e.g., Conner & Armitage, 1998), but is in both cases treated as a deviation from the core explanatory model. In the automatic behaviour approach, habitual behaviour is the focal point. And while theorigins of habits are not always well understood, we can note that habit formation and automatic reactions have at least partly been explained by mechanisms of operant and classical conditioning, which are just different ways of framing the assumption people that seek gratification and avoid unpleasant consequences of their behaviour, though it opens up for the possibility that people may get locked in habits that lead to e for them e pleasurable outcomes under previous conditions, but not necessarily under present conditions. As noted, reviewing the empirical evidence brought forth by the three streams of research is not the aim of this paper. However, we have noted that all three streams of research can point at a vast body of empirical results supporting their approach. This indicates that all three streams of research seem to tap core aspects of human behaviour, that they are complementary to each other, and that none of them can claim superiority in its ability to explain and predict human behaviour. It also suggests that when interest is guided by a practical problem like obesity, and not by a disciplinary interest in developing theory, an approach drawing on all three streams simultaneously is desirable. Not all three approaches have been linked to the longterm changes that may have caused the rise in obesity to the same degree. Econometric studies, with their high level of aggregation and frequent use of time-series data, are easily interpreted in terms of long-term changes and their impact on obesity. When behaviour is regarded mostly as the result of beliefs about the outcomes of the behaviour, perceived norms and values, and the ability to control one’s behaviour, as is the case in the reasoned behaviour approaches in psychology, persistent changes in patterns of behaviour should be related to persistent changes in these beliefs, or simply in the range of behaviours that are regarded as potential actions in any given situation. Since psychological studies on reasoned behaviour rarely rely on panel data, we know little about how such factors may have changed over time. We can speculate, though, that the factors discussed in the economic approaches may as well have resulted in people forming new beliefs about the availability of food and exercise opportunities, about qualities and prices, about the consequences of eating out vs. preparing meals, or about the seriousness of healthrelated consequences. In addition, the psychological approaches direct our attention to how social factors and lack of self-efficacy may reinforce lifestyle changes, and how they may become permanent patterns of behaviour due to habit formation and automatic elicitation. Framing policy options for preventing obesity Fig. 2 is an attempt to integrate factors possibly affecting behaviours related to energy balance across the three approaches discussed in this paper. Decisions on food intake

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Fig. 2. Policy instruments and factors affecting behaviours relevant for energy balance.

and physical activity are seen as affected by three groups of factors: a) economic factors, covering the prices of food in relation to other goods, the cost of time, the cost of adverse effects of unhealthy behaviour, and time preferences, all of which can affect behaviour based on the assumption of rational behaviour, b) social psychological factors, covering expected outcomes of healthy eating and of physical activity (both positive and negative), relevant norms and values, and perceived self-efficacy, which can affect behaviour based on the assumption of reasoned action, and c) environmental factors, both physical and symbolic, that can affect behaviour in automatic, unconscious ways. On the right hand side of the figure we distinguish between intention, action and maintenance, indicating that different factors may have different impacts on these phases of a change process. Looking over this range of factors in Fig. 2, it becomes clear that any particular policy instrument currently advocated for improving healthy eating or encouraging physical activity only covers a subset of them. Nutrition labelling aims at giving product information in a way that is credible and easily understandable; to the extent this aim is actually achieved it can improve people’s perceived self-efficacy in adopting and maintaining a healthy diet. It thus presupposes that people want to eat healthier, that the reason they don’t eat healthily now is a lack of information, and that people are able to understand and use the information. It does not address that for

some people it may be rational not to eat healthily, that healthy eating may by some be believed to lead to undesirable outcomes, and that there may be limits to conscious reasoning about everyday eating. Similar arguments apply to information related to physical activity, like calories burnt when performing certain activities. Product development and product reformulations that improve healthiness of the product or add health benefits likewise assume that people want to live healthier, that they appreciate the communication about the health benefits (as in a health claim) that accompany the product, that they find the outcomes promised desirable, and that these outcomes outweigh other disadvantages such as a higher price or a different taste of a food product. It does not take into account that people may infer undesirable outcomes from the promised health effects and is otherwise subject to much of the same limitations as nutrition labelling. In Fig. 2, the handles covered by product development and product reformulations are outcome expectancies, self-efficacy and perhaps time cost, when a functional food provides a more convenient way of healthy eating or when facilities for exercise make it more convenient to perform such activities. When product reformulation affects package/portion size or other physical food cues, it may also exert automatic effects on behaviour. Changes in product communication (e.g., regulation of advertising) can affect the formation of outcome expectancies, to the extent that some desirable consequences of

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(unhealthy) eating may no longer be promoted, or because unrealistic outcome expectancies about healthy eating are constrained. It can also affect the exposure to symbolic cues, like brands and logos that may have unconscious, automatic effects on behaviour. Education and counselling provides information on the costs and consequences of certain behaviours and shapes outcomes expectancies; when it is directed at relevant others it may indirectly affect behaviour via relevant others’ expectations. This goes for both healthy eating and physical activity. It can address psychological ambivalence by pointing out that healthy foods can also be tasty and healthy activities enjoyable. It can increase self-efficacy by developing competencies in performing healthy behaviours. Price measures (e.g., taxation), finally, affects the price of food relative to other goods and the relative prices of various foodstuffs. It could, in principle, also be used to lower prices for products and services aimed at increasing physical activity. Thus, taken together, the major policy instruments cover all the factors in Fig. 2. More importantly, any single instrument covers only a few of them. The groups of factors in Fig. 2 are derived from different approaches to the analysis of human behaviour, which are based on different assumptions and which cover different, complementary aspects. For this reason, no single policy instrument can be expected to be the major or even the dominant factor in changing energy-related behaviour. The groups of factors in Fig. 2 together shape energy-related behaviour, and their relative weight and the way they interact can be expected to differ between individuals, between situations, and also between the phases of intention formation, action and maintenance. We believe that much can be gained by drawing on the social sciences when analysing ways to affect energyrelated behaviour, and that when doing so it is important to retain a broad view that can accommodate different approaches. As we have shown, different branches of the social sciences make different assumptions on the determinants of human behaviour. We have limited our review to economic and psychological approaches; other social science branches like sociology, anthropology and political science could contribute with additional perspectives. While these approaches do compete against each other in the scientific arena, they supplement each other in the sense that they cover different aspects of human behaviour. Only by taking these different aspects into account simultaneously can there be progress in understanding and eventually changing energy-related behaviour. Acknowledgements This paper was commissioned by the Consumer Science Task Force of the European branch of the International Life Sciences Institute (ILSI Europe). Industry members of this task force are Coca-Cola Europe, Danone, International Nutrition Company, Kraft Foods, Nestle, Red Bull, Solae Europe and Unilever. It was coordinated by Fabienne

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