The relationship between masticatory and swallowing behaviors and body weight

The present study aimed to compare the main objective parameters of mastication among individuals with different body mass indexes. One hundred and sixty participants matched for gender and age were divided in the following groups according to their body mass index (BMI): Obese group (30 ≤ BMI < 35), Overweight group (25 ≤ BMI < 30), normal range group (18.5 ≤ BMI < 25) and underweight group (17 ≤ BMI < 18.5). Each group was composed by forty subjects. The maximum bite force, the masticatory performance, chewing rate and three variables related to swallowing (number of chewing cycles, chewing time, and median particle size) were assessed in all groups. The oral conditions, including the number of teeth, number of occlusal units and salivary flow (unstimulated and stimulated) were also evaluated. Regardless of the BMI, males had a larger bite force and better masticatory and swallowing performances than females. They also chewed faster than females. Individuals of the obese group had the largest median particles sizes (both after 20 chewing cycles and at the moment of swallowing), which indicates a less good masticatory performance. The median particle sizes were negatively correlated with the number of teeth and number of occlusal units in the obese group. We did not observe large differences in masticatory performance and swallowing variables among the four weight groups, although there was a tendency that individuals of the obese group swallowed larger particles. The results of this study do not support the existence of an "obese chewing style".