Aug 12 2007
Researchers in Britain say they have found that people often choose partners with similar body fat levels as themselves.
A team from Aberdeen University and the Rowett Research Institute in Scotland conducted a study involving 42 couples and discovered that people often choose partners with similar body fatness to their own as well as within their own social class.
The Aberdeen team say people also consider looks, height and race but they have also found those with about the same amount of fat are likely to be attracted to each other.
The scientists suggest that this "assortive mating" could be a factor in the worldwide obesity epidemic.
As a rule people now settle for their life partner later in life often in their mid to late thirties and also start families later.
Problems of overweight and obesity are becoming evident at a much younger age and children who have an overweight mother and father are possibly more susceptible to being overweight themselves.
The researchers measured the body composition of the 42 couples and found the amount of body fat in one person was proportionately very similar to that of their partner.
They measured the body fat using DXA (dual-energy X-ray absorptiometry), which is a much more accurate and reliable method of assessment than BMI.
Professor John Speakman, of Aberdeen University, says it is unclear how these associations come about and he speculates that the social activities of the overweight and obese people coincide, making them more likely to meet partners who are also overweight and obese.
Professor Speakman says such assortive mating for body fat is a relatively new phenomena as in the 1940s and 50s people married in their early 20s, often before they were overweight or obese.
He says would have been difficult then to assortively mate for body fatness because it would be impossible to distinguish somebody who was thin from somebody who was thin but going to become fat.
Choosing partners and having children much later along with becoming obese much younger makes it possible for potential partners to select each other on the basis of body fatness.
According to Professor Barry Popkin, director of the department of nutrition at the University of North Carolina, in 2006 for the first time in history the number of overweight people in the world overtook the number of malnourished.
The research is published in the current edition of the American Journal of Clinical Nutrition.