A comparison of body perceptions in relation to measured body composition in young Japanese males and females

The body composition of 139 Japanese females and 84 Japanese males (aged 18–30 years) was measured using anthropometry to assess gender differences in body perceptions in relation to their measured values. Participants were asked to rate perceptions of their own “heaviness” and “fatness” and these were compared to their BMI and percent body fat (%BF). Japanese females showed a significantly greater desire to lose body weight (−4.20 ± 0.6 kg) compared to males (0.27 ± 1.4 kg). Females also showed poor understanding of their “heaviness” and “fatness” in relation to actual body composition compared to males. The results confirmed distinct gender differences in body perception in relation to actual body composition and attitudes to weight management. Further promotion of “healthy” body image is recommended for the Japanese population.     

Effects of chewing on cognitive processing speed

In recent years, chewing has been discussed as producing effects of maintaining and sustaining cognitive performance. We have reported that chewing may improve or recover the process of working memory; however, the mechanisms underlying these phenomena are still to be elucidated. We investigated the effect of chewing on aspects of attention and cognitive processing speed, testing the hypothesis that this effect induces higher cognitive performance. Seventeen healthy adults (20–34 years old) were studied during attention task with blood oxygenation level-dependent functional (fMRI) at 3.0 T MRI. The attentional network test (ANT) within a single task fMRI containing two cue conditions (no cue and center cue) and two target conditions (congruent and incongruent) was conducted to examine the efficiency of alerting and executive control. Participants were instructed to press a button with the right or left thumb according to the direction of a centrally presented arrow. Each participant underwent two back-to-back ANT sessions with or without chewing gum, odorless and tasteless to remove any effect other than chewing. Behavioral results showed that mean reaction time was significantly decreased during chewing condition, regardless of speed-accuracy trade-off, although there were no significant changes in behavioral effects (both alerting and conflict effects). On the other hand, fMRI analysis revealed higher activations in the anterior cingulate cortex and left frontal gyrus for the executive network and motor-related regions for both attentional networks during chewing condition. These results suggested that chewing induced an increase in the arousal level and alertness in addition to an effect on motor control and, as a consequence, these effects could lead to improvements in cognitive performance.