Academic journal article North American Journal of Psychology

Ajzen's Theory of Planned Behavior as It Relates to Eating Disorders and Body Satisfaction

Academic journal article North American Journal of Psychology

Ajzen's Theory of Planned Behavior as It Relates to Eating Disorders and Body Satisfaction

Article excerpt

A relatively limited amount of theory-driven research has been conducted on the detection of eating disorders. Ajzen's theory of planned behavior (TPB) has been employed to predict behaviors in individuals, especially in the health field (1991). The theory states that an individual's behavior can be predicted based on their Attitudes, Subjective Norms, Perceived Behavioral Control, and especially, Intentions (See Figure 1).

Miller (2005) defined components of the theory illustrating each with the decision to implement a new program of regular exercise. Attitudes involve total beliefs about the consequences of particular behaviors weighted by evaluations of these beliefs, e.g., exercise improves physical health, looks and vigor, but exercise may be time-consuming, and is uncomfortable.

Subjective norms are comprised of influences from the person's social costs and benefits of exercise. A Subjective norm is the combined expectation from relevant individuals or groups, along with intentions to conform; perceptions of salient others' expectations about performing or not performing the target behavior (Ajzen & Fishbein, 1975). Perceived Behavioral Control is the expectation that a person can control an outcome. Behavioral intention is a function of both attitudes and subjective norms about the target behavior, predicting actual behavior. Behavioral intention assesses the relative strength of a person's intention to perform a behavior. Intentions imply the strength of one's commitment to engage in the behavior outcome.


Ajzen's TPB has previously predicted types of planned consummatory behaviors, such as vitamin supplement intake and diet. This is the first study applying Ajzen's TPB to the detection of eating disorders. This paper examines the theory and its potential as a useful tool for identifying and predicting disordered eating behaviors. Eating disorders are characterized by severe disturbances in eating habits. Three main types of eating disorders are anorexia nervosa (Mond, Robertson-Smith, and Vetere, 2006), bulimia nervosa (Mond, Hay, Rodgers, Owen, & Beumont, 2004), and binge eating disorder (Spitzer et al., 1992).

Several screening tools for eating disorders have been developed, including the Eating Disorder Inventory (EDI), the SCOFF Questionnaire, and the Eating Attitudes Test. The EDI is a 64-item self-report measure for eating traits and attitudes that is frequently used. It consists of eight subscales: Drive for Thinness, Bulimia, Body Dissatisfaction, Ineffectiveness, Perfectionism, Interpersonal Distrust, Interoceptive Awareness, and Maturity Fears. Joiner and Heatherton (1998) examined the EDI's intended factor structure and produced the first research that clearly supported it among nonclinical subjects. Since the dramatic increase in reports of both bulimia nervosa and anorexia nervosa from numerous Chinese and other non-Western countries, the EDI has been translated into multiple languages. Lee, Lee, Leung, and Yu (1997) attempted to show the reliability and validity of the Chinese version by administering the Chinese EDI to 1,172 undergraduates at the Chinese University of Hong Kong. Female participants had a significantly lower current BMI than their ideal BMI. In contrast, male participants' ideal BMI was significantly greater than their current BMI. The study verified that the Chinese EDI is reliable, economical, and has the potential to be a useful self-report tool for examining eating disorders.

Morgan, Reid, and Lacey (1999) developed and tested the SCOFF Questionnaire. This screening tool consists of 5 questions: 1) do you make yourself sick because you feel uncomfortably full; 2) do you worry you have lost control over how much you eat; 3) have you recently lost more than 1 stone (equivalent of 14 pounds) in a 3 month period; 4) do you believe yourself to be fat when others say you are too thin; and 5) would you say that food dominates your life. …

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