Researchers concluded a study tracking 800 children with asthma to determine why some kids outgrow asthma while others do not, and found that kids who were overweight or obese at the time they hit puberty were 3 times more likely to still have asthma.Their research points to obesity as a cause of asthma rather than an effect. This supports a similar 1998 study by Harvard Medical School that showed obese adults were 3 times more likely to develop asthma than thinner people. That study tracked the height, weight, and asthma rates of 90,000 nurses. While it is still not clear how obesity leads to asthma, researchers pointed out that excess weight compresses the airways, making them smaller and more affected by common asthma triggers such as coldness. Recent discovery of a common gene may link obesity with asthma. This gene is part of a family of proteins that cause insulin resistance?a precursor to obesity. Marc Rothenberg, director of Allergy and Clinical Immunology at the Cincinnati Children's Hospital, remarked that eventually drugs will be developed to block elements of obesity that will improve asthma as well. "We know that as obese people lose weight, their asthma tends to improve," he said.