Children who don't chew well are more likely to be obese

A research group from the University of Osaka, including Assistant Professor Takayuki Kousaka and Professor Kazunori Ikebe from the Department of Removable Prosthodontics and Gerodontology, Graduate School of Dentistry along with Assistant Professor Masatoshi Otsugu and Professor Kazuhiko Nakano from the Department of Pediatric Dentistry, has revealed for the first time in the world that children with low masticatory performance during their school years are more likely to become obese. The study, which surveyed 1,403 fourth-grade elementary school students in Osaka City, was published in the Journal of Dentistry.

In recent years, many children have been experiencing oral function problems, such as difficulty chewing hard foods or swallowing properly. Among these issues, masticatory performance is particularly important for proper nutrient intake and maintaining growth and health. Meanwhile, obesity during school age tends to transition into adult obesity and chewing habits and masticatory performance have been considered potential factors. However, how chewing habits and masticatory performance are related to obesity in school-age children has not been fully elucidated.

The research group signed a collaboration agreement with the Osaka City Board of Education, the Osaka City School Dental Association, and Lotte in April 2023, and conducted a large-scale survey of 1,403 fourth-grade elementary school students in Osaka City. Chewing habits were assessed using questionnaires, while masticatory performance was evaluated using measurement gum (Xylitol Chewing Check Gum). Obesity was evaluated by calculating the degree of obesity based on height and weight.

In the overall analysis, the odds ratios for obesity were 1.54 times higher for "eating fast," 1.73 times higher for "eating with mouth full," and 1.5 times higher for "lower masticatory performance." When analyzing only boys, the odds ratios for obesity were 1.84 times higher for "eating fast," 1.59 times higher for "eating with mouth full," and 1.63 times higher for "lower masticatory performance," all showing a relationship with obesity. In the analysis of girls only, no association was found between these factors and obesity. Furthermore, when both "eating fast" and "lower masticatory performance" were present, an association with obesity was found in both the overall analysis and the gender-specific analyses. In boys particularly, this combination resulted in an odds ratio for obesity of 3 times, the highest value observed.

These findings indicate the importance of guidance and measures that emphasize both "how to eat" and "how well one can chew" as countermeasures against obesity during school age, potentially serving as new guidelines for food education in schools and homes. Conveying the importance of masticatory performance during school age to schools and dentists nationwide is expected to contribute to children's healthy growth and improved awareness of oral health.

Ikebe commented: "The association between habits such as 'eating fast' and low masticatory performance with obesity has been revealed in studies targeting adults. However, there were few studies focusing on children, and sufficient evidence was lacking. We believe that the findings from this large-scale survey will serve as basic data for future research into how 'chewing' is related to overall health throughout life. We would like to express our sincere gratitude to the Osaka City Board of Education, the Osaka City School Dental Association, and Lotte Co., Ltd. for their cooperation in this research."

Journal Information
Publication: Journal of Dentistry
Title: Chewing habits and masticatory performance are associated with obesity in 9- to 10-year-old children: A cross-sectional study from the Osaka MELON Study
DOI: 10.1016/j.jdent.2025.105666