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Genes are responsible for more than three-fourths of abdominal adiposity, BMI
Nature trumps nurture in the obesity debate, according to results of a new study published in The American Journal of Clinical Nutrition.
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Previous studies have suggested that an environmental influence on obesity exists, but according to researchers from London, genetic influences on body mass index and abdominal adiposity are high among children born since the onset of the pediatric obesity epidemic.
More than 5,000 pairs of twins aged 8 to 11 years were analyzed for BMI, waist circumference and other genetic and environmental influences.
The analysis revealed that genes were responsible for 77% of the difference in BMI and waist circumference, whereas environmental influences were responsible for 23%.
These findings should serve as a reminder to clinicians “not to blame parents for their child’s obesity,” Jane Wardle, PhD, told Endocrine Today. “However, clinicians also need to help parents to understand that providing the best possible nutrition and activity environment for their children is an important part of parenting.”
Nature vs. nurture
Wardle and colleagues compared measurements from identical twins with those from fraternal twins who shared only half of their genes. The researchers reported a modest shared-environment effect for both BMI and waist circumference. Furthermore, although genetic influence on waist circumference was largely common to BMI (60%), a significant independent genetic effect (40%) also existed, according to the researchers.
Previous studies reported a strong genetic influence on weight variability among adults, according to Wardle, professor of clinical psychology, department of epidemiology and public health, University College, London.
Genes have not altered throughout the years, while environment has, according to the researchers. “This is still the case, even though rates of obesity have greatly increased,” she said.
Solomon K. Musani, PhD, Stephen Erickson, PhD, and David B. Allison, PhD, all of the University of Alabama at Birmingham, wrote in an accompanying editorial that these findings add to the “body of research on genetics of BMI in children by confirming that prior findings of a high heritability remain valid, even in the face of the current obesity epidemic, and by extending that research to show that the same general conclusions apply to waist circumference.” – by Katie Kalvaitis
For more information:
- Musani SK, Erickson S, Allison DB. Obesity-still highly heritable after all these years. Am J Clin Nutr. 2008; 87:275-276.
- Wardle J, Carnell S, Haworth CMA, Plomin R. Evidence for a strong genetic influence on childhood adiposity despite the force of the obesogenic environment. Am J Clin Nutr. 2008; 87:398-404.
These study findings are not surprising. Even though we are currently in the midst of an obesity epidemic we still see large variations in BMI between individuals that seem to track with parental and other family member's BMI. Since these twins were presumably raised in the same home, it is impossible to remove the environmental impact and the ideal study would include twins raised in different homes to better understand the nurture vs. nature question. However, environmental factors, such as healthy diet and exercise, are still overwhelmingly most important and need to be the focus of interventions aimed at the prevention and treatment of obesity, regardless of genetic propensity towards obesity.
– Kristin Nadeau, MD
Assistant Professor of Pediatrics
University of
Colorado Health Sciences Center