German 12-year panel study links weight trajectories with social and behavioral factors

Researchers analyzed data from the National Educational Panel Study adult cohort, following 8,209 people who were aged 28–55 in 2011/12. Cross-sectional regression models examined associations with BMI and overweight or obesity, while fixed-effects models assessed within-person changes across six measurement occasions through 2023/24. The exploratory analysis used multiple imputation for missing data.

BMI increased by 0.08 points per year on average, with the steepest rise during the first three years. At baseline, higher conscientiousness, tertiary education and more frequent sports participation were associated with lower BMI; higher extraversion was associated with higher BMI. Within individuals, increased sports participation was associated with lower BMI (−0.13), while increased household income (+0.10) and beginning to live with a partner (+0.29) were associated with higher BMI. Smoking was also associated with lower BMI (−0.52), a result the authors say may partly reflect weight gain after smoking cessation as smoking prevalence declined from 30% to 20%.

The study describes associations, not causal effects, and the authors characterize the analysis as exploratory. The unexpected association between neuroticism and lower baseline BMI requires replication using more comprehensive personality measures. The findings do not establish that changing any single factor will alter an individual’s weight trajectory.