Picture: A young couple 
People tend to go for partners
with a similar body fatness

When overweight people choose a partner who is also overweight, they pass on to their children a double dose of the genes that have made them susceptible to being overweight or obese. It has been long known that people tend to select people with characteristics similar to their own, similar height or class. Scientists call this assortative mating.

Scientists form the Rowett Research Institute and University of Aberdeen measured the body composition of forty-two couples using a sophisticated technique called dual-energy X-ray absorptiometry (DXA). Their results showed that the amount of body fat in one person was proportionately very similar to that of their partner’s, suggesting that people assortatively mate for body fatness.

“The idea that two people in a relationship have similar amounts of body fat is not new since previous studies have shown a link between couples and their body mass indices. It has also been suspected that BMI may be linked to other things that people choose their partner by, such as social class, or age,” said Dr Diane Jackson from The Rowett Research Institute.

“In our study, we corrected the results for all these other factors and we measured body fat using DXA, which is a much more accurate and reliable method of assessment than BMI. We also showed that the assortative mating for body fatness was not linked to the length of time that a couple had lived together.”

“What is currently unclear is how these associations come about. Perhaps the social activities of the overweight and obese people coincide, making them more likely to meet partners who are also overweight and obese,” said Professor John Speakman from The University of Aberdeen, who was also involved in the research.

For assortative mating for body fat to have contributed to the obesity epidemic it needs to have increased over time. The authors of the publication suggest that this has probably been the case.

MEDICA.de; Source: Rowett Institute