Self-Reported Eating Speed Is Dose-Dependently and Bidirectionally Associated with Long-Term Underweight- and Obesity-Related Weight-History Groups.

Background

Body mass index (BMI) changes across the life course, yet most studies rely on single time-point measures and focus primarily on obesity. Whether self-reported eating speed is associated with long-term weight-history groups, including persistent underweight, remains unclear.

Methods

This retrospective cohort study used Japanese health checkup data from 564,198 participants. According to BMI history in their twenties, participants were classified into normal-weight, underweight-history, and obesity-history groups. The underweight-history and obesity-history groups were further stratified according to the proportion of BMI measurements obtained during the entire observation period that indicated the respective weight state (0-25%, 25-50%, 50-75%, and 75-100%). Repeated BMI measurements were analyzed using linear mixed-effects models to characterize longitudinal differences across weight-history groups. Associations of self-reported eating speed with these groups were examined using sex-stratified multivariable logistic regression models.

Results

BMI differed clearly across weight-history groups in both sexes. Self-reported eating speed showed a dose-dependent and bidirectional association. In women, the odds of fast eating increased progressively with increasing obesity proportion, reaching an adjusted odds ratio (OR) of 1.47 (95% CI 1.40-1.53) in the 75-100% obesity group; in men, the corresponding OR was 2.40 (95% CI 2.35-2.45). Conversely, the odds of slow eating increased with increasing underweight proportion, reaching ORs of 1.89 (95% CI 1.82-1.96) in women and 2.45 (95% CI 2.35-2.56) in men in the 75-100% underweight group. In additional analyses, self-reported eating speed also showed persistence over follow-up: the mean proportion of follow-up responses matching the baseline self-reported eating-speed category was 72.33% (95% CI 71.25-73.42) in women and 79.90% (95% CI 79.55-80.25) in men in the 75-100% obesity group for fast eating, and 72.84% (95% CI 72.00-73.68) in women and 68.24% (95% CI 67.08-69.39) in men in the 75-100% underweight group for slow eating.

Conclusions

Self-reported eating speed showed a consistent bidirectional association with long-term weight-history groups in both sexes and remained relatively persistent over follow-up. These findings suggest that self-reported eating speed may be a behavioral correlate of long-term weight-history groups.