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OBJECTIVES: Over the past three decades, twin studies have shown variation in the heritability of obesity. This study examined the difference of body mass index (BMI) heritability (BMI-H) by population characteristics, such as sex, age, time period of observation and average BMI, as well as by broad social-environmental factors as indicated by country-level gross domestic product (GDP) per capita and GDP growth rate. METHODS: Twin studies that reported BMI-H and were published in English from January 1990 to February 2011 after excluding those with disease, special occupations or combined heritability estimates for country/ethnic groups were searched in PubMed. 32 studies were identified from Finland (7), the United Kingdom (6), the United States (3), Denmark (3), China (3), Netherlands (2), South Korea (2), Sweden (2) and four from other countries. Meta-regression models with random effects were used to assess variation in BMI-H. RESULTS: Heterogeneity of BMI-H is significantly attributable to variations in age (26, 000). BMI-H was higher in adolescents (median) on BMI-H were shown through stratified analyses by GDP. BMI-H was lower in countries of mid-level GDP, particularly those experiencing rapid economic growth. CONCLUSIONS: BMI-H is sensitive to age, time period of observation, average BMI, GDP and rapid economic growth.
Min et al. (Tue,) studied this question.