Young adults with obesity are more likely to be hospitalized, even if they have no other health problems, studies show. A patient arrived at Elmurst Hospital Center in Queens, N.Y., this month. A patient arrived at Elmurst Hospital Center in Queens, N.Y., this month.Credit...Kathy Willens/Associated Press Roni Caryn Rabin By Roni Caryn Rabin Published April 16, 2020 Updated April 17, 2020, 2:56 p.m. ET Obesity may be one of the most important predictors of severe coronavirus illness, new studies say. It’s an alarming finding for the United States, which has one of the highest obesity rates in the world. Though people with obesity frequently have other medical problems, the new studies point to the condition in and of itself as the most significant risk factor, after only older age, for being hospitalized with Covid-19, the illness caused by the coronavirus. Young adults with obesity appear to be at particular risk, studies show. The research is preliminary, and not peer reviewed, but it buttresses anecdotal reports from doctors who say they have been struck by how many seriously ill younger patients of theirs with obesity are otherwise healthy. No one knows why obesity makes Covid-19 worse, but hypotheses abound. Some coronavirus patients with obesity may already have compromised respiratory function that preceded the infection. Abdominal obesity, more prominent in men, can cause compression of the diaphragm, lungs and chest capacity. Obesity is known to cause chronic, low-grade inflammation and an increase in circulating, pro-inflammatory cytokines, which may play a role in the worst Covid-19 outcomes. ADVERTISEMENT Continue reading the main story Some 42 percent of American adults — nearly 80 million people — live with obesity. That is a prevalence rate far exceeding those of other countries hit hard by the coronavirus, like China and Italy. Obesity is defined by a measure called body mass index, which is based on a formula that divides one’s weight in kilograms by the square of one’s height in meters. Someone who is 5 feet 9 inches tall and weighs 203 pounds would have a B.M.I. of 30, which is considered obese. Thanks for reading The Times. Subscribe to The Times The new findings about obesity risks are bad news for all Americans, but particularly for African-Americans and other people of color, who have higher rates of obesity and are already bearing a disproportionate burden of Covid-19 deaths. High rates of obesity are also prevalent among low-income white Americans, who may also be adversely affected, experts say. More than half of Covid-19 deaths in the United States so far have been in New York and New Jersey, but the new findings mean the coronavirus could exact a steep toll in regions like the South and the Midwest, where obesity is more prevalent than in the Northeast. “If obesity does turn out to be an important risk factor for younger people, and we look at the rest of the United States — where obesity rates are higher than in New York — that will be of great concern,” said Dr. Roy Gulick, chief of infectious diseases at Weill Cornell Medicine. “We may see a lot more younger people being hospitalized.” ADVERTISEMENT Continue reading the main story Dr. Gulick’s review of data from the first 393 Covid-19 patients admitted to NewYork-Presbyterian/Weill Cornell Medical Center and NewYork-Presbyterian Lower Manhattan Hospital identified obesity as a risk factor for admission. He also found that among adults under the age of 54, half live with obesity, though the New York City obesity rate is only 22 percent.