Feeling Overweight or Skinny? It May Be Hereditary

Overweight

According to a study done at the University of Colorado Boulder, the way you perceive your body may be an inherited trait. The study tried to determine how heritable feelings regarding personal weight are, a decidedly novel idea. The findings seem to suggest that weight perception does have some sort of genetic component, and it seems to be stronger in females.

In Brief: Heritability

Heritability is measured on a scale of 0 to 1, with 0 meaning that genes have no influence on a trait, and 1 meaning that genes are the only influence on that trait. Most traits fall between 0.2 and 0.8 heritability.

It’s important to keep in mind that heritability is mainly a description of differences and heritability ratings will change depending on the population you’re looking at. Calculating the heritability of height, for instance, will give a larger score if you are examining a multicultural, immigration-heavy city than if you look at an area with a more homogenous population.

The Study

The researchers used data from the National Longitudinal Study of Adolescent to Adult Health, which sampled over 20,000 adolescents during their development into adulthood. The study started in 1994 and extended into 2008. The researchers focused on the weight-related data that was collected. The BMI of each participant was calculated during each of the four interviews that took place during the study and the participants were asked how they felt about their own weight. The response options were very underweight, slightly underweight, about the right weight, and so on.

Since hereditability for behavioral and psychological traits is much harder to determine than physical traits, the researchers were especially interested in the 700-plus pairs of twins that the study included. Since identical twins share all of the same genes, they are often used for determining the heritability of traits.

The findings suggest that, on average, self-perception about weight has a 0.47 heritability, which is stronger than the researchers’ calculated BMI heredity of 0.25. The heritability of self-perception was strongest among women, who had heritability scores of 0.39, 0.35, 0.40, and 0.50 for each of the four interview periods. By comparison, the men had a heritability of 0.10, 0.10, 0.23, and 0.03 across the four periods.

What This Means

Past research has suggested that perception of one’s own health is a good predictor of future health. Being more flexible in one’s self-perception makes it easier to take steps to improve and maintain health, and therefore improve longevity. Unfortunately, it is unclear how this applies to the study’s findings.

One annoyingly vague bit about the research is that it doesn’t specify what kind of self-perception it’s studying. Is it trying to determine heritability of self-perception aligning to objective BMI measurements (accuracy)? Misalignment (inaccuracy)? A specific type of perception? It would be nice if more clarity was provided since that could clear up any confusion.

In any case, due to the inherent difficulties in determining heritability for feelings, this research is definitely going to need replication and verification before broader conclusions can be drawn. In the meantime, it provides a novel call for further investigation into how genetics can affect feelings of self-perception and self-worth.


Sources:

Anderson, C., “Heritability,” genegeek web site, August 24, 2011; http://genegeek.ca/2011/08/heritability/, last accessed September 2, 2016.

Wedow, R., et. al., “Gender and genetic contributions to weight identity among adolescents and young adults in the U.S.,” Social Science & Medicine, 2016; http://dx.doi.org/10.1016/j.socscimed.2016.07.044.


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