Dietary restraint (including dieting to lose weight) is useful because it can help to prevent obesity. However, it is also associations with a number of unwanted consequences. These include depression (Rosen, Gross, & Vara, 1987), stress (Kagan & Squires, 1984), social anxiety (Rosen et al., 1987), a low self-esteem (Polivy, Herman, & Mcfarlane, 1994), and an increased risk of developing an eating disorder (Herman and Polivy, 1980 and Hsu, 1997). Dieting is also associated with poorer performance on a range of cognitive measures (Green and Rogers, 1995, Green and Rogers, 1998 and Wing et al., 1995). For example, compared with non-dieters, dieters appear to have a reduced ability to sustain attention (Rogers & Green, 1993), slower reaction times (Green and Rogers, 1995, Green et al., 2000 and Green et al., 1994), and poorer problem-solving performance (Green et al., 2003 and Green and Rogers, 1998).
Interestingly, these cognitive deficits appear to be mediated by psychological rather than physiological factors. This is because impairments exist in the absence of weight-loss (Green & Rogers, 1995) and because periods of enforced food deprivation fail to generate deficits in performance (Green et al., 1995 and Kretsch et al., 1997). Indeed, a recent study indicates that dieters may even experience a decrease in performance after eating a high-energy chocolate bar (Jones & Rogers, 2003). Based on this evidence, Green et al. (2003) have argued that performance is probably modulated by the demands that dietary restraint places on working memory capacity (Baddeley & Hitch, 1974). Consistent with this idea, dietary restraint is associated with a preoccupation with thoughts concerning food and weight (Laessle et al., 1996 and Williams et al., 2002), which is also correlated with the severity of the impairment (Green and Rogers, 1998 and Vreugdenburg et al., 2003).
We should be especially concerned, because dieting behaviour is now evident in early school ages (Braet and Wydhooge, 2000, Hill and Bhatti, 1995 and Hill et al., 1994). Self-reported dietary restraint has been identified in children as young as 9 years old (Hill and Bhatti, 1995 and Hill et al., 1994) and it is more common in girls than in boys (Thelen, Powell, Lawrence, & Kuhnert, 1992). A good predictor of attempts to lose weight is body-mass index (Schreiber et al., 1996). This may reflect an early onset of concerns about body image and self esteem (Conner et al., 1996, Gralen et al., 1990, Hill et al., 1992 and Lawrence and Thelen, 1995), possibly resulting from values inherited culturally from within the family (Davison, Markey, & Birch, 2000). Given this correspondence between adults and children, we sought to determine whether dietary restrained children exhibit the same kinds of cognitive impairment. This issue merits attention, because an impairment of this kind has the potential to impact on schooling and educational development.
