Psychological Explanations for Obesity

This model suggests that our food intake is on a spectrum, from hunger to satiety, upon which we have certain boundaries of how much and how little we will eat. When we enter the far ends of this spectrum, we are motivated to either eat or stop eating.

Herman and Polivy (1984) 

Hunger, satiety, and a biological indifference zone.

The individual will eat way past their satiety boundary once they have passed their restriction boundary, as they hold the belief that since they've 'ruined their diet' anyway, it doesn't matter, and they might as well eat whatever they want. 

Restraint theory suggests that people who restrict their food intake are actually more likely to overeat than those who do not due to passing self-imposed cognitive boundaries. The individuals attempt to change their eating behaviour cognitively rather than physiologically, and when they fail to stay within this boundary on the scale we discussed above, it can lead to binge eating, which subsequently contributes to obesity.

Binge eating is when you eat a large amount of food quickly, which can cause stomach pain and distress.

Restrained eaters are characterised as individuals who deliberately attempt to limit their food intake. 

These individuals tend to categorize foods into black and white categories of 'good' and 'bad' foods and create rules about how, when and what they will allow themselves to eat. 

A study by Herman and Mack (1975) demonstrated the restraint theory. 

Disinhibition (or counter-regulation effects) is a lack of ability to control behaviour, often characterised by an individual acting on impulses and disregarding consequences - they give up and have an all-or-nothing attitude to eating.

Yes.

The researchers found that, out of the three groups, the restricted diet group ate the most food over the seven weeks in which the study took place, due to episodes of disinhibition leading to binge eating. 

In a sample of 163 women, those who were characterised as restrained eaters lost more weight over six years than those who were not. This contradicts the ideas within the restraint theory. 

Dieting is where a person intentionally restricts their food intake to achieve a goal such as weight loss or improved health. 

Polivy and Heatherton (1992)

The spiral model indicates that dieting is motivated by comparison to an ideal self, which leads to body dissatisfaction and dieting to achieve one's ideal physique. Dieting behaviour is initially reinforced by positive outcomes, but eventually leads to psychological and physiological changes that make it harder for chronic dieters to lose weight.

Dissatisfaction,

A strength of the spiral model is that it has useful applications. For example, by instilling better self-esteem in adolescence, we can prevent young people from beginning the downward spiral of restrictive dieting.  

A criticism of the spiral model is that it does not address the issues that lead to low self-esteem, which starts this spiral in the first place.  

Ironic processes theory is where people on a diet tend to think about food much more than those who aren’t restricting their food intake.  

Daniel Wegner 

White bear.

He found almost all of these participants thought of a white bear, even more than those who had been specifically asked to think of one. 

In the study, a group of female students with the goal of reducing their intake of chocolate and crisps were given diet intentions in a negative form, for example, ‘When I am sad, I will not eat chocolate’. These negative statements were associated with higher amounts of ‘forbidden’ foods consumed.

The hedonic theory states those who struggle with their weight and maintaining diets/weight are sensitive to hedonic eating behaviours. The desire to eat is difficult to resist, and those who restrict their eating and are sensitive to the pleasures of eating are more likely to focus on the pleasures of eating than those who do not restrict their eating.

Here, participants’ saliva levels were measured before and after exposure to a hot pizza (desirable food) before and after they had lunch. The smell of this food prelunch produced a higher salivation response in restrained eaters than non-restrained eaters.

Obesity is defined as having too much body fat, or having a BMI of greater than 30. 

Physical and Psychological

Cognitive, Social and Environmental

Keys et al. (1950) conducted research on WWII soldiers and drew some interesting conclusions. They made American soldiers who had no interest in fighting ('conscientious objectors' ) start a starvation diet. 

When the soldiers started the starvation diet, the more they were denied food, the more they thought about it. This indicated to Keys et al. that the more restricted one's eating become, the more they think about food, which could make it a risk factor for obesity. 

Herman and Polivy (1975) 

The two factors that are part of Restraint Theory: Cognitive control and Paradoxical outcome.

Whilst there is an increased control over eating, this doesn't mean that the person will be able to successfully lose weight. What happens often is that the person is more preoccupied with food instead of less, due to thinking so much about what they can and can't eat or how much. Due to this cognitive control, the restrained eater doesn't eat when their body signals that they're hungry, nor stops eating when their body signals fullness. This leads to disinhibition of eating behaviour.

Restrained eating isn't the only cause of obesity, just how it starts. When disinhibition comes into play, it forms a dysfunctional cycle long with restrained eating. Disinhibited eating is a period of time that follows restrained eating, in which the obese person eats as much as they want. 

Disinhibited eating starts by being influenced by food cues that are internal (e.g. mood) and external (e.g. smells - environmental trigger, and media images - social trigger). Such cues are called disinhibitors, and they lead to a loss of control over restrained eating. This can even lead to a period of binge eating in some cases.

This is when the person believes that once they start to eat too much, or a food that they consider 'bad', they continue doing so since they believe they might as well eat everything they can since they won't be able to the next day/week.  

Herman and Polivy (1984) 

 feeling hungry to feeling full/satiated 

Biological processes - When we feel low energy levels, the body feels an aversive state of hunger, which motivates us to eat. When we feel full, there's an aversive feeling of discomfort, which motivates us to stop eating. 

Between these 2 boundaries is a space of biological indifference, in which there is minimal influence of biological processes. This is where we are neither hungry nor full, and cognitive or social factors have an effect on our eating behaviour. 

Restrained eaters have a self imposed satiety boundary (below the biological satiety boundary), which they set as the maximum amount they want to eat. However, when they break the self imposed boundary of their diet, then they eat way past the biological satiety boundary too. This leads to a passive and resigned 'all or nothing' approach, as mentioned beforehand.

Cognitive Behavioural Therapy 

This control is cognitive; by thinking about their food intake, they attempt to control their eating, which is usually an attempt to control their body size.