Obesity is a complex, multifactorial condition that is highly prevalent among adolescents. Eating “style”—in particular, behavioral aspects of chewing—may be an important aspect of body weight regulation. The epidemiologic literature shows that eating quickly is positively associated with excess body weight in adults. A similar relationship has also been observed in children, with those who are overweight taking larger bites and eating faster than children with lower body weights, which may promote overeating and weight gain. Any relationship between BMI or weight status and chewing features in children remains uncertain, as bite size and eating pace were assessed through visual observation within laboratory conditions or were self- or parent-reported. Studying eating and chewing features, particularly in regard to eating rate, has generally relied on number of bites per meal, self-report questionnaires about how fast a participant eats, or grams of food consumed per minute.

Comparing Chewing Features in a Natural Home Setting

For a study published in Pediatric Obesity, my colleagues and I recruited 42 adolescents (aged 15.3 ± 1.3 years; 20 female, 22 male), 21 of whom had a healthy weight and 21 who were overweight, to assess their chewing features using a smartphone-assisted wearable electromyographic (EMG) device (Table 1). The chewing features of each participant were assessed over a single evening, including the evening meal, in their natural home setting. The small wireless EMG device—developed by University of Otago Professor and Department of Orthodontics Head, Mauro Farella, DDS, PhD, PD—allowed recording of chewing features and eating occasions in a natural environment, in contrast with previous studies conducted in a laboratory setting.

Our findings showed a significant negative correlation between BMI z-score and chewing pace (R = −0.41; P = .007) and between BMI z-score and chewing time (R = −0.32; P = .039). In other words, our findings indicate that chewing rate is related to BMI in adolescents (Table 2), thus supporting the existence of an overweight-related “chewing style.” Adolescents with overweight have lower chewing pace and spent about 35% less time eating compared with leaner adolescents. These findings were unexpected as the assumption to have a faster chewing pace associated with overweight was shown to be the opposite in the current study. However, chewing pace in the current study was measured as the number of chewing strokes per second (Hz), a different variable than what has been referred to as “eating rate” in previous studies reporting eating rate as the number of bites per meal, grams per minute, or via qualitative questionnaires. Our findings add an extra objective dimension of the measured chewing features when testing the relation with body weight.

An Impetus for Further Weight-Management Interventions

Although the sample size is small, the current findings provide impetus for further work testing the effectiveness of changing eating behavior as a weight-management intervention in youth. This concept has been suggested in other initial studies about adjusting the rate of eating as an approach to weight management in children.

Future research is needed to identify how the way we eat can result in weight gain, or affects digestion, and eventually to explore potential application in weight control behavioral therapies, such as recommending chewing food for a longer time in young people.


Relationship between chewing features and body mass index in young adolescents