Women in America gain twice as much weight as men each decade because they exercise less and give birth, a new study finds.
Researchers at Brigham Young University (BYU), in Provo, Utah, found that the average woman puts on an average of 11.9 lbs every 10 years, compared to just 5.7 lbs for the typical man.
Scientists said less time spent playing sports or in the gym among women could be behind the more rapid weight gain.
They also blame pregnancy, pointing to a Dutch study that found women gained about 3.3 lbs to 4.4 lbs after having each child.
The study found women gain more weight than men over a decade. Scientists said this may be because they exercise less or due to pregnancy
About four in ten — or 70 million — American adults are obese, official figures suggest.
Some studies suggest women are more likely to fall into the obese category than men, with others suggesting there is little difference between the two.
Is it easier for women to gain weight than men?
A number of studies say it is easier for women to gain weight than men.
One of the key factors blamed for this is the difference in metabolism between the two sexes.
Women typically have more body fat and less muscle than men, meaning their body burns far fewer calories when resting.
Pregnancy is also on the list as another possible factor, because it triggers a woman to gain more weight. This can then prove hard to lose when a new baby arrives.
Yet more studies have pointed to the menopause as a factor, because of how it changes the hormones.
In the BYU study — published in the Journal of Obesity — scientists monitored a nationally representative sample of 13,000 American adults, with about half the group being female.
They tracked their weight for ten years, up until 2018.
Results showed a woman’s weight jumped by around 10 percent every decade on average.
But among men it rose by just 3.8 percent over the same time period.
Dr Larry Tucker, an exercise science expert who led the study, and colleagues said women may be gaining more weight because they exercise less.
In the paper, they wrote: ‘multiple studies indicate that women tend to be less physically active than men.’
To back this up they referenced a national-level study from 2009 which found exercise levels were ‘substantially higher’ among men.
The team also suggested pregnancy could be to blame, referencing a Dutch study from 2019 that found women gained about 3.3 lbs to 4.4 lbs after giving birth to a child and an Australian study from 2014 that also linked childbirth to weight gain.
But the scientists warned, however, that other papers had not found the same association.
Overall, the study also found that about half of American adults saw their weight rise by five percent over a decade.
A further third saw it rise by 10 percent, and a fifth saw it tick upwards by 20 percent or more.
People were more likely to gain weight when they were young or middle-aged the study found.
But once they were older many more were maintaining their weight or losing some.
Breaking the data down by race showed black adults put on the most weight (13.9 lbs), followed by Mexican Americans (9 lbs) and Other Hispanic groups (8.8 lbs).
The scientists said race was a ‘good indicator’ for the risk of gaining weight, which they put down to socio-economic differences between groups.
Tucker added: ‘The U.S. obesity epidemic is not slowing down. Without question, 10-year weight gain is a serious problem within the U.S. adult population.’