Attitudes towards obesity ‘learned in childhood’
MedWire News: Time constant factors, such as genetic heritability and habits formed during childhood, can significantly affect a person's body mass index (BMI) in adulthood, report UK researchers.
However, factors that change over time, such as social norms shaped by society's shifting attitudes towards weight and behaviors related to weight, or environmental factors like opportunities for exercise appear only to influence adolescents.
"Our study has important implications for obesity policy," remark Heather Brown (Newcastle University) and Jennifer Roberts (University of Sheffield) in the journal Obesity. It demonstrates "the importance of early childhood interventions and prevention programs to promote a healthier population," they say.
Using data from the Panel Study of Income Dynamics 1999-2007 the team investigated the effects of time constant factors and factors that change over time on BMI correlations among 236 adolescent (aged 10-18 years) siblings living in the same household (to isolate the influence of factors that change over time) and 838 adult (aged 27-55 years) siblings living apart, but who grew up in the same household.
Brown and Roberts report that the difference in mean sibling BMI converged over the study period. Indeed, the mean difference between adult siblings' BMI was 1.10 kg/m2 in 1999 and decreased to 0.97 kg/m2 in 2007. The mean difference between adolescent siblings' BMI was 2.00 kg/m2 in 2002, decreasing to 1.20 kg/m2 in 2007.
"This suggests that there are some factors either related to time constant factors such as genetic heritability or habits formed in childhood or factors that change over time such as the social spread of BMI that may be influencing this convergence."
Restriction maximum likelihood analysis revealed that time constant factors explained some of the overall correlation in sibling BMI for both cohorts of siblings. By contrast, only the adolescent group was influenced by factors that change over time.
"These results conform to findings from the behavioral genetics literature highlighting the importance of genetic factors in explaining weight outcomes," comment the authors.
Furthermore, "the results suggest that family background characteristics play an important role in explaining adult outcomes supporting our hypothesis regarding the formation of habits formed during childhood impacting on weight outcomes in adult," they conclude.
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By Nikki Withers