And now, we move onto a new report on obesity, with a surprising conclusion. Researchers say they have found a link between a woman's weight and the amount of work done around the home. Abc's cecilia vega takes a closer look tonight at a headline that is already drawing fire. Reporter: All that grueling housework? The homemaker walks miles every day. Reporter: A group of south carolina researchers say one reason modern women may be packing on the pounds? Is because they're not doing the heavy lifting like they used to. Even an efficiency expert would be staggered by the amount of indoor road work that the little woman takes as a matter of course. Reporter: Researchers compared activity logs kept by stay at home women from 1965 until today. And this is what they found. Then, women spent 25.7 hours a week dusting, mopping, cooking and washing. Fast forward to 2010, just 13.3 hours. The study says from 1965 until now, the average american woman who works at home has gained 22 pounds. People will see the headline from this study and say that you're telling women that they are fat because they're not doing housework. What we're saying is, there's been a decrease in physical activity across all of daily life. Reporter: Experts say that's not all. It's diet, genetics, economic status, more time in front of the tv. And they also question the motives of the study's sponsor -- coke. It makes no sense for coca-cola to be funding studies on causes of obesity, because they are one of the causes for obesity. Reporter: And in today's modern world, women fired back on twitter, saying, "excuse me? Today, a third of all american adults are obese. 50 years ago, the number was fewer than 10%. And both sexes areanding at an equal pace. Proof that when it comes to growing waistlines, there may be eqty after all. Cecilia vega, abc news, los angeles.