Fat people tend to pick fat ones as mates

22 August, 2007:

Fat people are more likely to choose overweight individuals as mates rather than normal-sized people.

A new study conducted in the United Kingdom provides additional evidence that obese people are more likely to select other obese people as mates. The study has been published in the August 2007 issue of the Journal of Clinical Nutrition.

This phenomenon is known as assortative mating, that is, when men and women tend to pick partners according to non-random attributes such as height, religion, age, and smoking habits.

Assortative mating also occurs when tall people tend to marry other tall people, and when individuals are inclined to marry within their own social class, within own educational class, and within own race.

Researchers have suggested that assortative mating by obesity could increase the already high prevalence of obesity by helping to pass on genes promoting excess weight to the next generation.

Till now, all studies investigating assortative mating for obesity have used body mass index or thickness of skin fold to measure obesity, and many have not accounted for other potential contributing factors, according to Dr John R Speakman and colleagues of the Rowett Research Institute in Aberdeen, Scotland.

Dr Speakman and his team used a technique called dual-energy X-ray absorptiometry (DXA) to get a more precise picture of levels of body fat in the participants of their study, which included 42 couples. They used statistical techniques to measure and account for the effects of age, the postal code area where people had grown up, and the amount of time they had been in a relationship.

The researchers found that assortative mating for body composition had indeed occurred, with heavier people winding up with heavier mates. It is not clear why this happens, Dr Speakman, says.

Leaner individuals may choose one another first, the researchers suggest, leaving overweight people a more limited mate pool to pick from.

Apart from the underlying reason, they add, the fact that people are becoming overweight and obese at earlier ages than ever before could be making assortative mating for obesity even more common, because it is “allowing singles in their late teens and early twenties to distinguish partners more easily with obese and lean phenotypes.”

Dr Speakman writes: “In the 1940s and 1950s, people mostly got married in their early 20s before they were overweight or obese. So it would have been difficult for them to assortatively 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. Nowadays, we choose partners and have children much later, but if we are going to become obese, on an average we do so much younger. This makes it possible for potential partners to select each other on the basis of body fatness.”