Dietary Restraint and Cognitive Performance Among Children

Among adults, dietary restraint is associated with a number of unwanted consequences, including depression, social anxiety, low self-esteem, and increased risk of developing an eating disorder. Dieting is also associated with poorer performance on a range of cognitive measures, such as poorer attention span, slower reaction times, and poorer problem-solving ability.

But, is the same true for children? Psychologist Jeffrey M. Brunstrom and colleagues at Loughborough University, UK, evaluated dietary restraint and cognitive performance in 44 girls (mean age: 10.1 years). The girls completed a simple reaction time task and the Tower of London (TOL) task (Appetite 2005;45:235). In the first task, the girls were seated at a computer and used the computer mouse to reach a target on the screen. In the second task, they used the mouse to move a series of blocks or pegs; the test puzzles became increasingly difficult, and the sessions were timed.

To measure dietary restraint, the researchers used the restraint scale of the Dutch Eating Behavior Questionnaire (Van Strien et al; Int J Eat Disord 5:747), 1986); the scale was modified to be more easily understood by children. Also, because pilot testing had shown that children could have an attention lapse when faced with computer-based tasks for a prolonged period, the authors’ program alternated between computer-based tasks and questionnaire items.

Restraint linked to longer reaction times

Children in the high-restraint group had significantly longer reaction times than did girls in the low-restraint group. The high-restraint group also took significantly longer to complete the TOL tasks than did the low-restraint group. Generally, the high-restraint group required more attempts to complete the task than the low-restraint group, although the difference was not statistically significant.

Thus, just as was noted earlier in adults, cognitive performance was poorer in girls who attempted to restrict dietary intake. According to Dr. Brunstrom and co-workers, usually reaction times shorten from infancy through childhood and slowly increase with age toward the end of the second decade of life. In the authors’ study, the average reaction time of the high-restraint group was approximately 50 milliseconds longer than that of the low-restraint group. This was similar to the degree of impairment seen in an earlier study with an adult sample (Green et al.; Physiol & Behav 1994; 55:447).

This is the first evidence that young girls with dietary restraint suffer from the same kinds of cognitive impairment found in adult populations, according to the authors. Dr. Brunstrom and his colleagues also found what they described as a negative “robust” relationship between high dietary restraint and academic performance (p =0.001).