Moderators and underlying mechanisms of stress-induced eating
The effect of stress on food intake varies across individuals, according to gender, bodyweight and eating style. However, little is known about the relative importance of these variables in stress-induced eating. Similarly, little research has addressed whether the effect of stress on intake differs according to stressor characteristics and food type. Psychological accounts of stress-induced eating have suggested a change in attentional processing of food stimuli when stressed, but this theory has not yet been directly tested. Physiological accounts of stress-induced eating propose that cortisol secretion during the physiological stress response has an appetitive effect, a theory that has received support from the laboratory, but has not been tested in the field. Six studies are presented in the present thesis, investigating the moderators and underlying mechanisms of stress-induced eating. Studies One and Two used questionnaire and diary methodologies to investigate the moderators of stress and snack intake. Study One indicated that increased intake was more prevalent in females and emotional eaters, and that the intake of crunchy foods particularly increased with stress. Study Two further highlighted that stressor type interacted with eating style, where emotional eaters, external eaters and disinhibitors increased intake in response to physical stressors, and high restrained eaters increased snack intake with work stressors. Studies Three, Four and Five investigated whether a change in attentional processes during stress could account for stress-induced intake in high external eaters. Study Three reported that external eaters increased their attention towards snack food words when stressed, while Study Four reported that external eaters attended towards unhealthy food words when stressed, but only at prolonged exposure times. Study Five did not provide further evidence for the theory, as stressed, external eaters did not attend towards food images. Study Six explored whether cortisol reactivity could account for stress-induced eating, comparing the snack intake of high and low cortisol reactors in response to laboratory and field stressors. The intake of high and low cortisol reactors did not differ in the laboratory. However, high reactors, but not low reactors, showed a positive association between hassles and snack intake in the field. The six studies combined to comprehensively investigate the moderators of stress-induced eating, and test two unexplored accounts of stress-induced eating, using both experimental and survey methodologies.