Discussion
obesity, masticatory behavior, weight loss, skeletal muscle mass
OBESITY
The masticatory indices for salad improved in both groups. By contrast, the number of chews and chewing duration for rice ball and number of chews for donuts also improved in the MIG. With regard to the body composition indices, the body weight, BMI, skeletal muscle mass, and body fat mass improved, and the HDL and LDL levels increased in both groups after 6 months of intervention. Meanwhile, the body fat percentage and FPG significantly decreased in the MIG. Among the biochemical indices, the HbA1c, AST, ALT, and GGT values improved significantly in both groups. Based on the rates of change between the two groups, the BMI, FPG, IRI, and HOMA-R values in the MIG were significantly lower than those in the CTG. In both groups, the content of nutritional and exercise guidance provided was the same; this result is considered an additional effect when masticatory guidance was added.A previous study reported that chewing gum between meals alone did not promote weight loss [In addition to regular nutritional guidance, the mastication intervention encouraged patients to recognize their masticatory behavior by measuring their masticatory indices in advance. Furthermore, the patients were encouraged to change their behavior by providing individual feedback and guidance on mastication. It is conceivable that because of this intervention, although chewing instruction was provided once a month by a registered dietician, changes in chewing behavior were observed after 6 months. This was expected to influence the three daily meals. Specifically, this study quantified the number of chews and chewing duration during nutritional guidance and provided valuable results regarding the usefulness of chewing guidance along with the results. The Japanese Ministry of Health, Labor and Welfare recommends chewing each mouthful of food 30 times, which has been implemented in many studies [After giving feedback on the number and duration of mastication before intervention, we instructed the participants to increase the number of mastications. Since the number and duration of mastications vary depending on the food item consumed, it is necessary to provide guidance on how to select food, how to cook it, and how to reduce the size of each bite. The recommended number and duration of mastications for each ingredient have not been reported in this study and should be investigated in future studies.This study has some limitations. First, only female patients with obesity were included in this study. Therefore, whether the same results would be observed in male patients with obesity remains unknown. Previous studies have reported sex-related differences in mastication characteristics [