Within-Person Longitudinal Associations Between Obesity-Related Eating Behaviors and Physical Activity Among Older Adults: A Three-Wave Random-Intercept Cross-Lagged Study.

Objectives: This study examined the within-person longitudinal associations between obesity-related eating behaviors and physical activity among community-dwelling Chinese older adults. Methods: Three waves of data were collected at three-month intervals from 1256 adults aged 65 years or older across 17 urban and rural communities. Physical activity was measured using the Physical Activity Rating Scale-3, and obesity-related eating behaviors were assessed using the seven-item Sakata Eating Behavior Scale Short Form. The eating-behavior scale was reverse-scored so that higher scores represented fewer problematic behaviors. The analysis examined longitudinal measurement invariance, gender differences, and prospective within-person associations using a random-intercept cross-lagged panel model. Results: The analysis identified small reciprocal within-person associations between obesity-related eating behaviors and physical activity. Occasions characterized by fewer problematic eating behaviors than usual were followed by higher-than-usual physical activity at the next wave. Higher-than-usual physical activity was likewise followed by fewer problematic eating behaviors. These associations remained similar after adjustment for the available demographic covariates. Men reported higher average physical activity, while women reported fewer problematic eating behaviors, but changes over time did not differ by gender. Conclusions: Physical activity and obesity-related eating behaviors showed small bidirectional within-person associations across three-month intervals. This reciprocal pattern suggests that the two behaviors are modestly connected within everyday routines and supports examining them together when studying health behavior dynamics in later life.