People Born Around Middle Of 20ᵗʰ Century May Have Greater Link Between Genes And High BMI Than People Born Earlier In The Century.

The obesity epidemic in the United States began approximately in the late 1970s. Birth cohort can thus be conceptualized as a proxy for increased exposure to obesogenic environmental factors. More recent birth cohorts were exposed to these environmental factors at earlier developmental stages and for a greater fraction of their lives compared with older birth cohorts. Numerous environmental changes occurred in tandem during the obesity epidemic.25- 27 Energy intake in the United States increased by on average 7% in men and 22% in women from 1971 to 2000.28- 30 Sugar-sweetened beverage consumption increased rapidly,31,32 and these beverages apparently exacerbate effects of genetic variants on BMI.33 Physical activity patterns, which may offset the effect of genetic risk factors on obesity,4,24 have also changed.34 http://jama.jamanetwork.com/article.aspx?articleid=2532014