To our knowledge this is a first report on the association between FA and actimetry-derived 24-h RAR characteristics. Studies of 24-h RAR characteristics in BED patients have been previously conducted [17, 28]. Individuals with BED have been shown to have a decrease in amplitude and MESOR [17, 28]. Women with BED during multidisciplinary therapy  had higher IS values than the control group, lower L5 and M10 values, and no statistically significant differences in IV and acrophase of 24-h RAR. The authors concluded that multidisciplinary therapy leads to improved sleep-wake rhythm characteristics in patients with BED, primarily IS and L5. In this study, we have shown that the nature of the association between FA and 24-h RAR characteristics differs significantly from those in BED patients. We noted a positive association between SC of FA and MESOR and did not detect an association between SC and the amplitude and acrophase of 24-h RAR. In addition, we have shown that of all the studied nonparametric indicators of 24-h RAR, only the IV index was significantly associated with SC. It has been repeatedly shown that BED and FA have similarities [29–31]. Both eating disorders are more common in women, as well as in overweight individuals. Both types of eating disorders are characterized by a close association with impulsivity and depression . At the same time, the difference between these two types of eating disorders, mainly related to behavior, was noted; there was the least close correlation between the behavioral component of BED and SC of FA . It can be assumed that actimetry-derived 24-h RAR is a sensitive method for detecting differences between these two types of eating disorders. To test the validity of this assumption, it is necessary to conduct comparative studies of 24-h RAR characteristics in BED and FA.
The present study showed that an objective assessment of motor activity rhythm is a convenient and sensitive method for studying the associations between the states of the circadian system and eating behavior. Two features of motor activity rhythm characteristic of persons with FA and emotional eating were identified. Firstly, it was shown that individuals with symptoms of FA and emotional eating had a more pronounced fragmentation of the 24-h rhythm of motor activity. Previously, it was shown that FA is more often detected in young people with a late chronotype . At the same time, there was no association between SJL and FA . This negative result may be due to the fact that MCTQ is not sensitive enough to study the association between the states of the circadian system and eating behavior. SJL is primarily a measure of the instability of the phase of circadian rhythm during a calendar week. Judging by the data we obtained, fragmentation of the circadian rhythms of motor activity is a characteristic trait of persons with FA and emotional eating. The relationship between FA and emotional eating has been repeatedly noted in the past [18, 19], indicating similarities between these two characteristics of eating behavior.
Secondly, we showed that persons with high SC of FA have a higher average daily level of motor activity (MESOR), and that the profile of the daily rhythm of motor activity of people with restraint and emotional eating behaviors is characterized by an increased level of motor activity during the daytime (M10). These results were unexpected, since it is well known that FA is a risk factor for obesity [20, 21]. Obesity, in turn, is associated with a decrease in the level of motor activity [32, 33]. However, there is quite often a weak or nonlinear association between SC of FA and the morphological signs of obesity [34–36]. In addition, FA and emotional eating are just some of the many risk factors for obesity. A distinctive character trait of people with FA and emotional eating is impulsivity of behavior [37, 38]. A positive association between impulsivity and the level of motor activity in the daytime has been repeatedly noted in previous research [39, 40].
The data obtained indicate the presence of a significant association between FA and sociodemographic indicators: higher SC of FA was more often detected in women and in overweight people, and there was also a decrease in the SC of FA with age. These data are consistent with the results of previous studies [41, 42] and indicate that the study was conducted on a representative sample.
Strengths And Limitations
The study has a number of limitations. A significant bias towards women among the study participants could have affected the results of the analysis. The cross-sectional design of the study did not allow us to judge the causal associations between the studied indicators. The study involved practically healthy people whose anthropometric data and eating behavior were evaluated by self-assessment, so the results obtained cannot be used in clinical practice.