Genetic and Environmental Effects on Body Mass Index (BMI) Fluctuation Across the Adult Life Course and Its Associations With Baseline BMI and BMI Change: An Individual‐Based Study of 14 Longitudinal Twin Cohorts
Authors' conclusion
BMI fluctuation was predominantly explained by unique environmental effects, with moderate heritability that varied across life stages with no evidence of sex-specific genetic effects. Genetic and environmental factors contribute to how BMI fluctuation is associated with BMI change.
Study context
- Population
- Adults in 14 longitudinal twin cohorts (54% women; 22,714 complete twin pairs, 9761 monozygotic), BMI trajectories from ages 18 to 99 years
- Participants
- 58,311 adults14 twin cohorts
- Comparison
- Men vs Women
- Outcome
- BMI fluctuation: average squared residual between observed and expected BMI around individual trajectories; genetic and environmental contributions
Methodological details14 longitudinal twin cohorts, individual-based, structural equation modelling, linear mixed-effects models
- 14 longitudinal twin cohorts
- Individual-based
- Structural equation modelling
- Linear mixed-effects models
Pooled result
As reported in the abstract
Variance in BMI fluctuation explained by additive genetic (a2) and unique environmental (e2) effects
| Group | a2 | e2 |
|---|---|---|
| Men | 0.20 | 0.80 |
| Women | 0.29 | 0.71 |
a2
Men0.20
Women0.29
e2
Men0.80
Women0.71
Further pooled results
| Outcome | Men | Women |
|---|---|---|
| Peak genetic contribution to BMI fluctuation by life stage | ||
| a2 at ages 31-50 | 0.36 | — not stated in the abstract |
| a2 at ages 51-65 | — not stated in the abstract | 0.36 |
— not stated in the abstract
Associations of BMI fluctuation with baseline BMI and BMI change
- Higher baseline BMI associated with greater fluctuation; greater directional BMI change associated with less fluctuation
- Higher BMI at ages 18-30 associated with greater subsequent BMI fluctuation across later adulthood stages
- Associations driven by both genetic and unique environmental factors
Original publication
Genetic and Environmental Effects on BMI Fluctuation Across the Adult Life Course and Its Associations With Baseline BMI and BMI Change: An Individual‐Based Study of 14 Longitudinal Twin Cohorts. Diabetes Obes Metab. Published 25 June 2026. doi:10.
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