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Understanding the obesity epidemic

BMJ 2019; 366 doi: (Published 03 July 2019) Cite this as: BMJ 2019;366:l4409

Linked research

Quantifying the impact of genes on body mass index during the obesity epidemic

  1. Rockli Kim, research associate1,
  2. Dong Hoon Lee, postdoctoral research fellow2,
  3. SV Subramanian, professor13
  1. 1Harvard Center for Population and Development Studies, Cambridge, MA, USA
  2. 2Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA
  3. 3Department of Social and Behavioral Sciences, Harvard T.H. Chan School of Public Health, Boston MA 02115, USA
  1. Correspondence to: SV Subramanian svsubram{at}

A greater understanding of the variation between people is key

Globally, mean body mass index (BMI) increased by 0.4 kg/m2 and 0.5 kg/m2 each decade for men and women respectively between 1980 and 2008.1 This focus on average changes in BMI has underpinned the case for population-wide approaches to obesity prevention and treatment, either by modifying the “obesogenic environment”2 or by advocating whole population changes in behavior such as increasing physical activity3 and reducing consumption of high energy food.4 This approach, however, ignores the substantial underlying variation in BMI within a population. Variation is also incorrectly assumed to be constant across different populations and over time.567

The development and availability of polygenic risk scores in population based data have substantially expanded research on the contribution to the obesity epidemic of genetic variation and its interaction with obesogenic environments.234 Polygenic risk scores summarize thousands of genetic variants with predictive capability across diverse disorders or traits. …

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