TUESDAY, Jan. 16, 2018 (HealthDay News) -- The death rate in the United States isn't decreasing as it has in years past, and some experts blame the opioid epidemic. But a new study suggests America's increasing girth is what's really behind the slowdown.
Excess weight led to nearly 200,000 excess deaths in 2011. And overall, those extra pounds reduced life expectancy by almost one year at age 40, researchers determined.
"Rising levels of body mass index [BMI] have prevented the United States from enjoying the full benefits of factors working to improve mortality," wrote study author Samuel Preston and his colleagues. Preston is a professor of sociology at the University of Pennsylvania.
Body mass index is a rough estimate of a person's body fat based on height and weight measurements.
Heart disease deaths had declined consistently for nearly 40 years. These declines have slowed or stopped altogether, according to the researchers. Rates of decline in cancer deaths have also slowed, they said.
At the same time, rates of obesity have been rising in the United States. From 1976 to 1980, 15 percent of Americans were obese. By 2014, 38 percent of Americans were classified as obese, the researchers said in background notes.
Dr. Mitchell Rosen, chief of obesity surgery at Lenox Hill Hospital in New York City, said obesity is linked to mortality in several ways.
"Obesity is the biggest cause of type 2 diabetes, and it promotes all of the risk factors that cause heart disease, such as high blood pressure and cholesterol," said Rosen, who wasn't involved with the study.
"Obesity also promotes sleep apnea, which is a leading cause of sudden death and motor vehicle accidents," he added. "Obesity affects every organ system in the body." It's also linked to a number of cancers.
To get a better idea of obesity's impact on death rates, Preston and his colleagues gathered data from a national health survey from 1988 through 2010. The survey included more than 25,000 Americans between 40 and 84 years old. The researchers also looked at related death data through 2011.
Using a statistical model, the researchers assessed how much of the slowing death rate trend could be explained by rising body mass index.
They found that in 2011 America's increase in BMI reduced life expectancy by 0.9 years by age 40 -- almost 11 months. The statistical model also estimated that 186,000 excess deaths occurred that year due to rising BMI in the United States.
Dr. Rekha Kumar is an endocrinologist with New York-Presbyterian/Weill Cornell Medical Center's Comprehensive Weight Control Center in New York City.
Kumar said many experts believe an increase in "deaths of despair" -- such as opioid overdoses or suicides -- has slowed improvements in death rates.
"Opioids are definitely lowering life expectancy in younger people. But my feeling was that obesity was a contributor overall," said Kumar, who was not part of the study.
Kumar said these findings suggest the need for physicians and policymakers to deal with obesity from a public health perspective.
"The last time we saw a dip in life expectancy was with HIV/AIDS, and we reacted to that crisis and developed new drugs," she said.
"But there's an extreme bias with obesity because it's considered a behavioral condition, and insurers and Medicare and Medicaid are slow to provide coverage for obesity treatments," Kumar added. "We only see coverage for obesity medications about 30 percent of the time."
Kumar said it's important to understand that losing weight is "more complicated than 'eat less, exercise more.'"
She recommended seeing a doctor who specializes in weight management who can help you successfully shed pounds and keep them off.
Rosen agreed that there's no easy answer for losing weight. "Obesity may be tougher to treat than cigarette smoking," he said.
"The best strategy is not to gain weight when you're young," he said. But if you do have excess weight to take off, he added, you need to change what you're eating.
The study is in the Jan. 15 issue of PNAS.
To learn more about the health effects of obesity, visit the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.