A study investigated if, among healthy individuals, experimental evidence is limited to the assertion that eating restraint increases with a cognitive bias for food. The results of this study were published in Clinical Psychology Review.
To investigate whether food restriction causes attentional and inhibitory control, researchers conducted a subgroup meta-analysis of the studies of methods of measuring eating restraint.
This subgroup meta-analysis included studies published in peer-reviewed journals before May 2021 that measured a healthy adult individuals’ general cognitive performance, attentional bias, memory bias, response inhibition or impulsivity, measured in the presence of non-food or food stimuli. The studies included the means and standard deviations of cognitive bias when comparing individuals with higher and lower restraint, or they included the correlation coefficient between cognitive biases and eating restraint scores.
The 37 studies that the researchers included had high heterogeneity with researchers conducting exploratory meta-analyses of the attentional bias tasks involved in the studies.
The researchers found evidence of increased cognitive biases and impulsivity in the high-restraint group compared with the low-restraint group when they examined studies using the restraint scale (RS) (meta-analytic standardized mean difference [Hedges’ g] = 0.33, P =.005).There was no significant difference between the effect sizes of subgroups of studies that used various scales to measure eating restraint, or between high- and low-restraint groups in studies that used the Three-Factor Eating Questionnaire (TFEQ), the Dutch Eating Behaviour Questionnaire (DEBQ), or concern for dieting subscale of the RS (RS-CD).
In the exploratory meta-analysis of attentional bias studies, the investigators found that in studies utilizing the food-Stroop task, interference from food words were consistent (I2 <0.01%) and studies using the food-SCT were moderately inconsistent (I2 = 52%). Neither task showed that eating restraint was linked with performance on tasks.
Food distraction decreased with eating restraint as three studies of food distraction with low heterogeneity (I2 < 10%) showed.
The four studies of general impulsivity without food cues had low heterogeneity (I2 <0.01%) with no correlation between impulsivity and eating restraint.
Researchers found no evidence that eating restraint was linked with attentional bias or distraction by food cues.
“Substantial heterogeneity may have been expected, given the wide range of tasks that were included in this meta-analysis, many with unknown psychometric properties. It should be noted, however, that these tasks were all included because they are often used interchangeably in the literature when authors wish to make the point that those scoring high on eating restraint have biased cognitions and biased behavioural tendencies in the presence of food cues,” the researchers said.
“The results of this meta-analysis demonstrate that this is a flawed summary of the literature, however, because it does not appear possible to reliably relate ‘cognitive bias’ to eating restraint. Instead the sizeable heterogeneity and inconsistency across studies suggests that there is a wide dispersion of effect sizes and that different paradigms may be measuring different underlying constructs. As such, it is misleading to make sweeping statements about the relationship between cognitive and behavioural biases for food and eating restraint because a unitary construct of ‘cognitive bias for food’, in this context, likely does not exist.”
Watson P, Le Pelley M. A meta-analysis of the relationship between eating restraint, impaired cognitive control and cognitive bias to food in non-clinical samples. Clin Psychol Rev. November 2021. doi: 10.1016/j.cpr.2021.102082