Caloric Intake at Lunch Does Not Mediate the Impact of Eating Rate on Weight Gain Among Healthy Adults: Longitudinal Cohort Study

Abstract

Purpose

This study aims to evaluate causal relationships among eating rate, caloric intake, and weight gain using longitudinal data and to clarify how caloric intake mediates the effect of eating rate on weight gain.

Design

A longitudinal cohort study with a 4-year follow-up.

Setting

Data were collected from Daihatsu Co, Ltd employees, a major Japanese automobile manufacturer with 4 plants in Japan.

Subjects

Of the 12,816 working-age Japanese individuals who underwent health checkups in 2020, 7,784 without excess weight or non-communicable diseases were included.

Intervention

The eating rate was self-reported, and caloric intake was calculated based on cafeteria meal choices.

Measures

Annual change in body mass index (BMI), calculated as the difference in BMI between consecutive years.

Analysis

Mediation analyses using a mixed-effects model were conducted to assess whether caloric intake mediates the effect of eating rate on BMI.

Results

Caloric intake in the fast-eating and ordinal-eating groups exceeded that of the slow-eating group by 19.21 kcal [9.28, 29.13] and 10.01 kcal [1.20, 18.81], respectively. Higher caloric intake was associated with a more significant BMI increase, rising by .09 [.06, .13] per interquartile range increase. The proportion of mediated impact among the impact of eating rate is .19% [.09, .32].

Conclusion

Faster eating independently contributes to BMI increases, with minimal mediation by caloric intake. Interventions targeting eating pace may prevent obesity, though the study population may limit generalizability.