What is bulimia nervosa?
Bulimia nervosa is a serious psychiatric illness characterized by recurrent episodes of binge eating in combination with inappropriate compensatory behaviours (e.g., self-induced vomiting) and an overvaluation of weight and shape.
Bulimia nervosa is becoming increasingly common in both men and women, with global prevalence rates estimated to be around 0.5% and 2.0%, respectively 1 Smink, F. R., Van Hoeken, D., & Hoek, H. W. (2012). Epidemiology of eating disorders: incidence, prevalence and mortality rates. Current psychiatry reports, 14(4), 406-414.
The seriousness of this illness is underscored by the fact that bulimia nervosa is associated with a range of negative outcomes, including premature mortality, depression, anxiety, and substance-use disorders, low self-esteem, sexual dysfunction, self-harm behaviours, and interpersonal problems2 Fairburn, C. G. (2008). Cognitive behavior therapy and eating disorders. Guilford Press. .
In order to receive a diagnosis of bulimia nervosa, the person must display:
- Recurrent episodes of binge eating
- Recurrent inappropriate compensatory behaviours in order to prevent weight gain, such as self-induced vomiting, misuse of laxatives, diuretics, or compulsive exercise.
- These behaviours both occur, on average, at least once a week for three months.
- Regarding weight and shape as central to one’s self-worth (i.e., overvaluation of weight/shape).
The Core Symptoms of Bulimia Nervosa
Let’s now delve into what the core symptoms of bulimia nervosa are.
Simply put, binge eating means eating uncontrollably. However, there’s a little more to it than this.
We can usefully distinguish between two different types of binge eating:
The first is objective binge eating, which occurs when one eats an unusually large amount of food in a short period of time (~2 hours) accompanied by a sense of loss of control.
The second is subjective binge eating, which occurs when one eats what is perceived as an excess amount of food, but in reality is not objectively large, while also experiencing a sense of loss of control3 Fairburn, C. G., Cooper, Z., & Shafran, R. (2003). Cognitive behaviour therapy for eating disorders: A “transdiagnostic” theory and treatment. Behaviour research and therapy, 41(5), 509-528. .
Other important characteristics of binge eating include:
- Eating much more rapidly than normal
- The foods consumed during a binge are usually so-called “forbidden foods”
- The binge eating causes one to experience profound guilt and shame
- Eating during the episode us usually hidden from others.
Purging may be either compensatory of non-compensatory.
Compensatory purging is the use of purging behaviour to minimize the effects on weight or specific episodes of eating that the person views as extreme. If the purging is compensatory, it is linked to these episodes, follows them, and only occurs when they occur.
In non-compensatory purging, the behaviour functions as a more routine form of weight control (like dieting), in which the purging behaviour need not coincide with excessive episodes of eating4 Fairburn, C. G., Cooper, Z., & Shafran, R. (2003). Cognitive behaviour therapy for eating disorders: A “transdiagnostic” theory and treatment. Behaviour research and therapy, 41(5), 509-528. .
Common purging behaviours include:
- Self-induced vomiting
- Misuse of laxatives or diuretics
- Compulsive exercise
It is important to point out that these methods to purge are relatively ineffective. For example, self-induced vomiting expels less than 50% of the calories consumed while laxatives and diuretics do not rid any of the calories consumed5 Kaye, W. H., Weltzin, T. E., Hsu, L. G., McConaha, C. W., & Bolton, B. (1993). Amount of calories retained after binge eating and vomiting. American Journal of Psychiatry, 150, 969-969. . Despite this, people largely use these methods because they believe it will positively affect their weight and shape.
Dietary restraint refers to the conscious attempt to restrict food intake with the aim of regulating body weight6 Polivy, J., & Herman, C. P. (1985). Dieting and binging: A causal analysis. American psychologist, 40(2), 193. . Dietary restraint is the symptom of bulimia nervosa that directly causes the binge eating behaviour.
Dietary restraint is usually expressed through multiple and specific demanding diet rules that dictate what, when, and how much one can eat. Common examples of these rules include: not eating anything after 6pm, avoiding any form of carbohydrate, or eating fewer than 1500kcal per day.
We can usefully distinguish between three different forms of dietary restraint.
- Delayed eating: occurs when one goes for a very long period of time (around 6 waking hours) without eating or drinking anything with the goal of influencing weight and shape.
- Food avoidance: occurs when a person completely forbids oneself to eat a certain food or food group.
- Restriction: occurs when a person eats less food than their body needs.
So, why is dietary restraint a problem, and how does it cause binge eating? There are a couple of different mechanisms explaining how and why dietary restraint cause bingeing7 Polivy, J., & Herman, C. P. (1985). Dieting and binging: A causal analysis. American psychologist, 40(2), 193. . These are:
Dieting makes us very hungry, so hunger and related physiological mechanisms will eventually overpower the cognitive control over eating (i.e., the diet rules), resulting in binge eating.
The strict and inflexible diet rules that govern when, what, and how much one can eat become too hard to sustain over a long period, and the inevitable breaking of these rules will induce an all-or-none reaction. This reaction from the diet “failure” causes the binge eating.
Overvaluation of weight and shape
Overvaluation of weight and shape is considered to be the underlying core psychopathology of bulimia nervosa. This essentially means that all of the other clinical features of bulimia nervosa stem from this overvaluation8 Fairburn, C. G. (2008). Cognitive behavior therapy and eating disorders. Guilford Press. .
So, what does an overvaluation of weight and shape mean?
It means that, in people with bulimia nervosa, judgements of self-worth are largely contingent on the person’s ability to control their weight and shape. In other words, whereas most people evaluate themselves or their self-worth on a variety of life domains, such as their work performance, academic achievement, relationship status etc, people with bulimia nervosa usually evaluate their self-worth (or how good they are as a person) on how much they weigh or what they look like.
This overvaluation is a cognitive feature, and it can be expressed in a variety of different ways, including the obsessive body checking (e.g., self-weighing, looking in front of the mirror for long periods, pinching areas of the body to assess for fat levels etc.) and body avoidance (e.g., wearing baggy clothes as a disguise, complete refusal to be weighed etc.), comparison making, feelings of fatness, body dissatisfaction and preoccupation, and dietary restraint.
The above symptoms are considered the core symptoms of bulimia nervosa – they occur in all people with the condition.
Let’s now discuss some other important symptoms that may occur in many, but not all, people with bulimia nervosa.
Like overvaluation of weight an shape, people with clinical perfectionism judge themselves largely, or even exclusively, in terms of working hard toward, and meeting, personally demanding standards in areas of life that are important to them (including the domain of weight and shape) 9 Shafran, R., Cooper, Z., & Fairburn, C. G. (2002). Clinical perfectionism: A cognitive–behavioural analysis. Behaviour research and therapy, 40(7), 773-791. .
Some features of clinical perfectionism include:
- Overvaluation of achieving in valued domains of life
- Marginalisation of other life aspects
- Rigorous pursuit of personally demanding standards despite this having negative impact on performance and causing impairment in other life domains
- Continuous performance checking
- Fear of failure
Core Low Self-Esteem
Core low self-esteem refers to the tendency for one to have a global negative view of the self. People with bulimia nervosa who have low self-esteem generally try to better their self-view via achieving in the domain of weight, shape, and eating.
Low self-esteem is a problem because it intensifies the overvaluation of weight and shape, hampers a person’s motivation for changing their illness, and may predict poorer outcomes in treatment10 Fairburn, C. G. (2008). Cognitive behavior therapy and eating disorders. Guilford Press. .
An inability to cope appropriately with certain emotional states is also another symptom of bulimia nervosa. Usually this intolerance is of adverse mood states, such as anger, anxiety or depression, but in some cases there is intolerance of positive mood states.
Instead of accepting changes in mood and dealing appropriately with them, people with bulimia nervosa engage in what may be termed “dysfunctional mood modulatory behaviour.” This reduces their awareness of the triggering mood state (and the associated cognitions), and also neutralises it, but at a personal cost. The dysfunctional mood modulatory behaviour takes the form of binge eating or purging11 Fairburn, C. G., Wilson, G. T., & Schleimer, K. (1993). Binge eating: Nature, assessment, and treatment (pp. 317-360). New York: Guilford Press. .
|↑1||Smink, F. R., Van Hoeken, D., & Hoek, H. W. (2012). Epidemiology of eating disorders: incidence, prevalence and mortality rates. Current psychiatry reports, 14(4), 406-414.|
|↑2, ↑8, ↑10||Fairburn, C. G. (2008). Cognitive behavior therapy and eating disorders. Guilford Press.|
|↑3, ↑4||Fairburn, C. G., Cooper, Z., & Shafran, R. (2003). Cognitive behaviour therapy for eating disorders: A “transdiagnostic” theory and treatment. Behaviour research and therapy, 41(5), 509-528.|
|↑5||Kaye, W. H., Weltzin, T. E., Hsu, L. G., McConaha, C. W., & Bolton, B. (1993). Amount of calories retained after binge eating and vomiting. American Journal of Psychiatry, 150, 969-969.|
|↑6, ↑7||Polivy, J., & Herman, C. P. (1985). Dieting and binging: A causal analysis. American psychologist, 40(2), 193.|
|↑9||Shafran, R., Cooper, Z., & Fairburn, C. G. (2002). Clinical perfectionism: A cognitive–behavioural analysis. Behaviour research and therapy, 40(7), 773-791.|
|↑11||Fairburn, C. G., Wilson, G. T., & Schleimer, K. (1993). Binge eating: Nature, assessment, and treatment (pp. 317-360). New York: Guilford Press.|