Couples weigh more on average: contracting promotes weight gain

The weight of love: When couples move in together, they increase

Research has shown that married people usually live longer than singles. On the other hand, couples are often thicker than single people. It has so far been unclear how changes in relationships affect body weight and when couples gain the most. Researchers have now found that it is primarily the contraction that leads to weight gain.

Partners have an impact on their own health

Various scientific studies have already shown that a partnership can also affect physical wellbeing. For example, researchers at University College London reported that many people live healthier thanks to the partner, partly because they put off unhealthy behaviors. And U.S. scientists found that living together in a marriage improves health because the partner has lower levels of the stress hormone cortisol. However, on average, couples weigh more than single people. A German study has now shown what leads to weight gain.

Marriage does not lead to weight gain

Couples have a higher body weight than singles - whether with or without marriage certificates. But contrary to what was often assumed, it is less the marriage than the first move that leads to weight gain.

Scientists from the Max Planck Institute for Human Development, the University of Mannheim, the University of Leipzig and the German Institute for Economic Research have found this out.

To arrive at their results, the researchers analyzed data from 20,950 individuals between 19 and 100 years over a period of 16 years.

The results of the study were published in the journal "Health Psychology".

Change in everyday eating habits

The researchers found that couples who move in together gain about twice as much as couples in the first four years of marriage.

This effect persists, even if important influences such as age, childbirth, sport, smoking, health status or stress are excluded.

"This means that this weight gain is primarily related to the change in relationships," explains Ralph Hertwig, co-author of the study and director at the Max Planck Institute for Human Development, in a statement.

“Because a change in the relationship status often also means a change in everyday eating habits - for example having breakfast together, which alone might not have taken place or would have been more modest. In general, you eat more in society and therefore consume more calories, ”says the expert.

Both sexes increase the most in divorces

When couples separate, the body mass index (BMI), which puts a person's body weight in relation to their height, decreases again largely to the value before contracting in women and men.

As stated in the communication, this corresponds to the prediction of the so-called marriage market hypothesis that people looking for a partner try to lower their body weight, since this is associated with more attractiveness.

Interestingly, both genders increase the most in divorces that follow separations. One possible explanation for this is that many people - especially men - are in a new relationship when they divorce.

"With regard to weight gain, contracting and divorcing are important time windows for prevention," says Jutta Mata, professor of health psychology at the University of Mannheim and associate scientist at the Max Planck Institute for Educational Research.

“So far, social influences - including changes in relationships - have hardly been taken into account in the development of obesity. Instead, individual factors such as knowledge or willpower were discussed, ”explains the researcher.

“Our results show that an unmarried man who is slightly overweight before moving in will gain an average of about 7.5 kilograms after having lived together for at least four years without marriage certificates, married, separated and divorced. This increases his general mortality risk by up to 13 percent. ”(Ad)

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