The role of diet-congruent cues in short term food intake

Weight loss attempts and weight loss maintenance are often unsuccessful in part due to dieters’ vulnerability to palatable food cues. Exposure to diet-congruent cues has thus been proposed as a goal priming strategy to counteract this vulnerability. Diet-congruent cues increase the salience of diet thoughts and reduce subsequent snack intake in restrained eaters. However, little is known about the impact of diet-congruent cue exposure on food intake in those actively dieting. Given that dieters hold goals to lose weight, diet-congruent cues might be particularly salient to dieters and cue diet-consistent behaviour when dieters are conflicted by food temptations. Thus, the current thesis aimed to examine the effects of diet-congruent cues on subsequent energy intake in dieting and non-dieting women. Specifically, as food is closely associated with dieting, the current research tested the effects of diet-congruent food cues. The salience of diet and tempting thoughts were also assessed to identify the potential mechanism of goal priming.
Two online surveys identified snacks (Chapter 4; n = 157) and meal related foods (Chapter 6; n = 230) that women most associated with dieting to lose weight or temptation. Using these databases, four laboratory studies were conducted. Using a between-subjects design, Chapter 3 showed that subtle exposure to diet-congruent images reduced dieters’ intake of a LFSW snack by 40% compared to dieters exposed to non-food control images. Chapter 4 adopted a within-subjects design and exposed participants to the sight and smell of a diet-congruent (fresh orange) or tempting (chocolate orange) food. Dieters consumed 40% less chocolate after exposure to the diet-congruent cue compared to the tempting cue. However, when this study was replicated with an additional non-food control condition, dieters’ intake was unaffected by the diet-congruent odour, possibly due to a lower motivational state. Chapter 6 measured the effects of consuming a diet-congruent preload on meal intake in a repeated measures design, and found dieters reduced meal intake by 21% compared to intake of a tempting and control preload. Contrary to predictions, dieters’ reduced energy intake did not correspond with increased salience of diet thoughts in diet-congruent conditions relative to control or tempting conditions (Chapters 3, 5 and 6). However, consistent with a goal priming explanation, only dieters were responsive to diet-congruent cues, whereas, non-dieters’ energy intake did not differ after diet-congruent cue exposure compared to tempting or control cues.
This thesis has identified diet-congruent food cues which improve dieters’ short term control over food intake in laboratory settings. Future research should examine the efficacy of diet-congruent cues to reduce the energy intake of active dieters in more naturalistic and applied settings and contribute to their attempts to resist temptation.