The grit personality trait, eating behavior, and obesity among Japanese adults: a cross-sectional study

Obesity is a chronic disease influenced by genetic, cultural, environmental, and psychosocial factors, making it difficult to manage through individual effort alone. Despite this complexity, obesity is often attributed to a lack of willpower and poor control over eating behaviors, contributing to stigma. However, research on this issue remains limited. This study quantified the extent to which multidimensional eating behaviors statistically explained the association between obesity and grit, which shared characteristics with self-control.

We conducted a cross-sectional study involving Japanese adults across a wide range of age groups. Grit was measured using the 8-item Short Grit Scale. Multidimensional eating behaviors were measured using the Japanese version of the 21-item Three-Factor Eating Questionnaire-R21, including uncontrolled eating, emotional eating, and cognitive restraint. Obesity was defined as a body mass index ≥ 25.0 kg/m². A series of logistic regression models were created to analyze the association between grit and obesity with and without eating behaviors. Mediation analyses using the Karlson-Holm-Breen method were performed.

Of the 1,641 adults, 26.8% had obesity. Higher grit level was associated with a lower likelihood of obesity, less uncontrolled and emotional eating, and higher cognitive restraint. Grit was positively associated with cognitive restraint and negatively associated with uncontrolled and emotional eating; these multidimensional eating behaviors statistically accounted for the association between grit and obesity. Uncontrolled and emotional eating fully accounted for the association, whereas cognitive restraint partially accounted for it. These findings are consistent with the possibility of mediation through eating behavior in the relation between grit and obesity.

Our findings suggest that healthcare providers and policymakers should prioritize addressing multidimensional eating behaviors that explain the link between grit and obesity rather than on grit itself. Identifying and managing impairments in eating behavior rather than attributing obesity to an individual's lack of willpower may help reduce stigma and support effective obesity prevention strategies.