Genetic and environmental effects on weight gain from young adulthood to old age and its association with body mass index in early young adulthood: an individual-based pooled analysis of 16 twin cohorts
Authors' conclusion
Genotype influences BMI changes across adulthood, with its effect varying by age and sex. Environmental effects are the main drivers of adult BMI changes, highlighting the role of modifiable factors in long-term weight regulation.
Study context
- Population
- Adults from 16 longitudinal twin cohorts (56% women; 55,657 complete twin pairs, 42% monozygotic); three stages: young adulthood-early middle age, late middle age, old age
- Participants
- 111,370 adults16 twin cohorts
- Comparison
- Men vs Women
- Outcome
- Genetic and environmental contributions to BMI changes from young adulthood to old age and their correlation with BMI in early young adulthood
Methodological details16 longitudinal twin cohorts, structural equation modeling, linear mixed effects and delta slope methods
- 16 longitudinal twin cohorts
- Structural equation modeling
- Linear mixed effects and delta slope methods
Pooled result
As reported in the abstract
Heritability (a²) of BMI changes
- A², young adulthood-early middle age (18-50 years): men
- 0.29
- A², young adulthood-early middle age (18-50 years): women
- 0.26
- A², late middle age (51-64 years): men
- 0.05
- A², late middle age (51-64 years): women
- 0.16
- A², old age (>65 years): men
- 0.13
- A², old age (>65 years): women
- 0.18
- Non-shared environmental effects (e²): men
- 0.71-0.95
- Non-shared environmental effects (e²): women
- 0.74-0.84
Further pooled results
Average, kg/m²
| Outcome | Men | Women |
|---|---|---|
| Average BMI increase per year · young adulthood-early middle age (18-50 years) | 0.18 | 0.15 |
- Average BMI increase per year — Average BMI increase per year at older ages
- ≤0.07 kg/m²
Correlation of BMI in early young adulthood (18-30 years) with later BMI changes
- Men: greater early BMI associated with lower later BMI changes (r)
- −0.22 to −0.13
- Men: genetic correlation (rA)
- −0.27
- Men: non-shared environmental correlation (rE)
- −0.22 to −0.14
- Women: positive association (r)
- 0.05-0.28
- Women: genetic correlation (rA)
- 0.27-0.51
Original publication
Genetic and environmental effects on weight gain from young adulthood to old age and its association with body mass index in early young adulthood: an individual-based pooled analysis of 16 twin cohorts. Int J Obes (Lond). Published 25 December 2025. doi:10.
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