Research has explored possible mechanisms for the overeating shown by restrained eaters.
These are described below and include the causal model of overeating, the boundary model of overeating, cognitive shifts, mood modification, denial, escape theory, overeating as relapse and the central role for control.
The causal analysis of overeating
The causal analysis of eating behaviour was first described by Herman and Polivy (Herman and Mack 1975; Herman and Polivy 1980, 1988; Polivy and Herman 1983, 1985). They suggested that dieting and bingeing were causally linked and that ‘restraint not only precedes overeating but contributes to it causally’ (Polivy and Herman 1983). This suggests that attempting not to eat, paradoxically increases the probability of overeating – the specific behaviour that dieters are attempting to avoid. The causal analysis of restraint represented a new approach to eating behaviour and the prediction that restraint actually caused overeating was an interesting reap-praisal of the situation. Wardle (1980) further developed this analysis and Wardle and Beales (1988) experimentally tested the causal analysis of overeating. They randomly assigned 27 obese women to either a diet group, an exercise group or a no-treatment control group for seven weeks. At weeks four and six all subjects took part in a laboratory session designed to assess their food intake. The results showed that subjects in the diet condition ate more than both the exercise and the control group, supporting a causal link between dieting and overeating. From this analysis the overeating shown by dieters is actually caused by attempts at dieting.
The boundary model of overeating
In an attempt to explain how dieting causes overeating, Herman and Polivy (1984) developed the ‘boundary model’, which represented an integration of physiological and cognitive perspec-tives on food intake. The boundary model is illustrated in Figure 6.6.
According to the model, food intake is motivated by a physiologically determined hunger boundary and deterred by a physiologically determined satiety boundary. In addition, the boundary model suggests that the food intake of restrained eaters is regulated by a cognitively determined ‘diet boundary’. It indicates that dieters attempt to replace physiological control with cognitive control which represents ‘the dieter’s selected imposed quota for consumption on a given occasion’ (Herman and Polivy 1984: 149). Herman and Polivy (1984) described how, after a low calorie preload, the dieter can maintain her diet goal for the immediate future since food intake remains within the limits set by the ‘diet boundary’. However, after the dieter has crossed the diet boundary (i.e. eaten something ‘not allowed’), they will consume food ad lib until the pressures of the satiety boundary are activated. The boundary model proposes a form of dual regulation, with food intake limited either by the diet boundary or the satiety boundary.
The boundary model has also been used to examine differences between dieters, binge eaters, anorexics and normal eaters. This comparison is shown in Figure 6.7.
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Hunger Satiety
No preload Preload
Hunger
Dieter
Satiety
No preload Preload Diet
Figure 6.6 A boundary model explanation of overeating in dieters
Hunger Diet Satiety
Hunger Satiety
Hunger
Diet Satiety
Hunger Satiety
Capacity Dieter
Disinhibited dieter
Binge eater
Anorexic
Normal eater
Figure 6.7 A comparison of the boundaries for different types of eaters
Cognitive shifts
The overeating found in dieters has also been understood in terms of shifts in the individual’s cognitive set. Primarily this has been described in terms of a breakdown in the dieter’s self-control reflecting a ‘motivational collapse’ and a state of giving in to the overpowering drives to eat (Polivy and Herman 1983). Ogden and Wardle (1991) analysed the cognitive set of the dis-inhibited dieter and suggested that such a collapse in self-control reflected a passive model of overeating and that the ‘what the hell’ effect as described by Herman and Polivy (1984) con-tained elements of passivity in terms of factors such as ‘giving in’, ‘resignation’ and ‘passivity’.
In particular, interviews with restrained and unrestrained eaters revealed that many restrained eaters reported passive cognitions after a high calorie preload, including thoughts such as ‘I’m going to give in to any urges I’ve got’ and ‘I can’t be bothered, it’s too much effort to stop eating’ (Ogden and Wardle 1991). In line with this model of overeating, Glynn and Ruderman (1986) developed the eating self-efficacy questionnaire as a measure of the tendency to overeat.
This also emphasized motivational collapse and suggested that overeating was a consequence of the failure of this self-control.
An alternative model of overeating contended that overeating reflected an active decision to overeat, and Ogden and Wardle (1991) argued that implicit within the ‘what the hell’ effect was an active reaction against the diet. This hypothesis was tested using a preload/taste test para-digm and cognitions were assessed using rating scales, interviews and the Stroop task which is a cognitive test of selective attention. The results from two studies indicated that dieters responded to high calorie foods with an increase in an active state of mind characterized by cog-nitions such as ‘rebellious’, ‘challenging’ and ‘defiant’ and thoughts such as ‘I don’t care now, I’m just going to stuff my face’ (Ogden and Wardle 1991; Ogden and Greville 1993; see Focus on Research 6.1, p. 153). It was argued that, rather than simply passively giving in to an over-whelming desire to eat, as suggested by other models, the overeater may actively decide to overeat as a form of rebellion against self-imposed food restrictions. This rebellious state of mind has also been described by obese binge eaters who report bingeing as ‘a way to unleash resentment’ (Loro and Orleans 1981). Eating as an active decision may at times also indicate a rebellion against the deprivation of other substances such as cigarettes (Ogden 1994) and against the deprivation of emotional support (Bruch 1974).
Mood modification
Dieters overeat in response to lowered mood and researchers have argued that disinhibitory behaviour enables the individual to mask their negative mood with the temporary heightened mood caused by eating. This has been called the ‘masking hypothesis’ and has been tested by empirical studies. For example, Polivy and Herman (1999) told female subjects that they had either passed or failed a cognitive task and then gave them food either ad libitum or in small controlled amounts. The results in part supported the masking hypothesis as the dieters who ate ad libitum attributed more of their distress to their eating behaviour than to the task failure.
The authors argued that dieters may overeat as a way of shifting responsibility for their negative mood from uncontrollable aspects of their lives to their eating behaviour. This mood modifica-tion theory of overeating has been further supported by research indicating that dieters eat more than non-dieters when anxious, regardless of the palatability of the food (Polivy et al.
1994). Overeating is therefore functional for dieters as it masks dysphoria and this function is not influenced by the sensory aspects of eating.
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The role of denial
Cognitive research illustrates that thought suppression and thought control can have the para-doxical effect of making the thoughts that the individual is trying to suppress more salient (Wenzlaff and Wegner 2000). This has been called the ‘theory of ironic processes of mental control’ (Wegner 1994). For example, in an early study participants were asked to try not to think of a white bear but to ring a bell if they did (Wegner et al. 1987). The results showed that those who were trying not to think about the bear thought about the bear more frequently than those who were told to think about it. Similar results have been found for thinking about sex (Wegner et al. 1999), thinking about mood (Wegner et al. 1993) and thinking about a stigma (Smart and Wegner 1999). A decision not to eat specific foods or to eat less is central to the dieter’s cognitive set. This results in a similar state of denial and attempted thought suppression and dieters have been shown to see food in terms of ‘forbiddenness’ (e.g. King et al. 1987) and to show a preoccupation with the food that they are trying to deny themselves (Grilo et al. 1989;
Ogden 1995a). Therefore, as soon as food is denied it simultaneously becomes forbidden which translates into eating which undermines any attempts at weight loss. Boon et al. (2002) directly applied the theory of ironic processes of thought control to dieting and overeating. They used a factorial design and a standard preload taste test paradigm. Restrained and unrestrained eaters were given a preload that they were told was either high or low in calories and then were either distracted or not distracted. Their food intake was then measured in a taste test. The results showed that the restrained eaters ate particularly more than the unrestrained eaters in the high calorie condition if they were distracted. The authors argued that this lends support to the theory of ironic processes as the restrained eaters have a limited cognitive capacity, and when this capacity is ‘filled’ up by the distraction their preoccupation with food can be translated into eating. In a similar vein Soetens et al. (2006) used an experimental design to explore the impact of trying to suppress eating-related thoughts on subsequent thoughts about eating. The sample was divided into restrained and unrestrained eaters; the restrained eaters were then divided into those who were either high or low on disinhibition. The results showed that the disinhibited restrained eaters (i.e. those who try to eat less but often overeat) used more thought suppres-sion than the other groups. The results also showed that this group also showed a rebound effect following the thought suppression task. This means that restrained eaters who tend to overeat try to suppress thoughts about food more often, but if they do, they think about food more often afterwards.
Escape theory
Researchers have also used escape theory to explain overeating (Heatherton and Baumeister 1991; Heatherton et al. 1991, 1993). This perspective has been applied to both the overeating characteristic of dieters and the more extreme form of binge eating found in bulimics, and describes overeating as a consequence of ‘a motivated shift to low levels of self-awareness’
(Heatherton and Baumeister 1991). It is argued that individuals prone to overeating show com-parisons with ‘high standards and demanding ideals’ (Heatherton and Baumeister 1991: 89) and that this results in low self-esteem, self-dislike and lowered mood. It is also argued that inhibitions exist at high levels of awareness when the individual is aware of the meanings associ-ated with certain behaviours. In terms of the overeater, a state of high self-awareness can become unpleasant as it results in self-criticism and low mood. However, such a state is accom-panied by the existence of inhibitions. The individual is therefore motivated to escape from self-awareness to avoid the accompanying unpleasantness, but although such a shift in self-awareness may provide relief from self-criticism, it results in a reduction in inhibitions
thereby causing overeating. Within this analysis disinhibitory overeating is indicative of a shift from high to low self-awareness and a subsequent reduction in inhibitions.
Overeating as a relapse
Parallels exist between the undereating and overeating of the restrained eater and the behaviour of the relapsing smoker or alcoholic. The traditional biomedical perspective of addictive behav-iours viewed addictions as being irreversible and out of the individual’s control (see Chapter 5).
It has been argued that this perspective encourages the belief that the behaviour is either ‘all or nothing’, and that this belief is responsible for the high relapse rate shown by both alcoholics and smokers (Marlatt and Gordon 1985). Thus the abstaining alcoholic believes in either total abstention or relapse, which itself may promote the progression from lapse to full-blown relapse. In the case of the restrained eater, it is possible that they too believe in the ‘all or nothing’ theory of excess which promotes the shift from a high calorie lapse to the ‘what the hell’ characterized by disinhibition. This transition from lapse to relapse and the associated changes in mood and cognitions is illustrated in Figure 6.8.
These parallels have been supported by research suggesting that both excessive eating and alcohol use can be triggered by high risk situations and low mood (Brownell et al. 1986b; Grilo et al. 1989). In addition, the transition from lapse to relapse in both alcohol and eating behavi-our has been found to be related to the internal attributions (e.g. ‘I am to blame’) for the ori-ginal lapse (e.g. Ogden and Wardle 1990). In particular, researchers exploring relapses in addictive behaviours describe the ‘abstinence violation effect’ which describes the transition from a lapse (one drink) to a relapse (becoming drunk) as involving cognitive dissonance (e.g.
‘I am trying not to drink but I have just had a drink’), internal attributions (e.g. ‘It is my fault’) and guilt (e.g. ‘I am a useless person’) (Marlatt and Gordon 1985). These factors find reflection in the overeating shown by dieters (Ogden and Wardle 1990).
The role of control
The interview data from a study of 25 women who were attempting to lose weight provide further insights into the mechanisms behind overeating (Ogden 1992). The results from this study indicated that the women described their dieting behaviour in terms of the impact on their family life, a preoccupation with food and weight and changes in mood. However, the concept of self-control transcended these themes. For example, when describing how she had prepared a meal for her family, one woman said, ‘I did not want to give in, but I felt that after preparing a three-course meal for everyone else, the least I could do was enjoy my efforts’.
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Dieting
• Attempting to eat less
Lapse
• Eating something not allowed
Relapse
• Overeating
• Belief in all or nothing
• Lowered self-esteem
• Self-blame
• Lowered mood
• Cognitive shift
Figure 6.8 The ‘what the hell’ effect as a form of relapse
The sense of not giving in suggests an attempt to impose control over her eating. In terms of the preoccupation with food, one woman said, ‘Why should I deprive myself of nice food?’ and another said, ‘Now that I’ve eaten that I might as well give in to all the drives to eat’. Such state-ments again illustrate a sense of self-control and a feeling that eating reflects a breakdown in this control. In terms of mood, one woman said that she was ‘depressed that something as simple as eating cannot be controlled’. Likewise this role of self-control was also apparent in the women’s negative descriptions of themselves, with one woman saying, ‘I’m just totally hopeless and weak, and though I hate being fat I just don’t have the willpower to do anything about it’.
In summary, restraint theory indicates that dieting is linked with overeating and research inspired by this perspective has explored the processes involved in triggering this behaviour.
Studies have used experimental and descriptive designs and suggest a role for physiological boundaries, cognitive shifts, mood modification, denial, a shift in self-awareness and control.
These are illustrated in Figure 6.9.