The impact of obesity and overweight on the U.S. economy has eclipsed $1.7 trillion, an amount equivalent to 9.3 percent of the nation's gross domestic product, according to a new Milken Institute report on the role excess weight plays in the prevalence and cost of chronic diseases.

The estimate includes $480.7 billion in direct health-care costs and $1.24 trillion in lost productivity, as documented in America's Obesity Crisis: The Health and Economic Impact of Excess Weight (www.milkeninstitute.org/publications/view/944). The study draws on research that shows how overweight and obesity elevate the risk of diseases such as breast cancer, heart disease, and osteoarthritis, and estimates the cost of medical treatment and lost productivity for each disease.

For example, the treatment cost for all type 2 diabetes cases -- one of the most prevalent chronic diseases connected to excess weight -- was $1.21 billion and indirect costs were $215 billion. On an individual basis, that comes to $7,109 in treatment costs per patient and $12,633 in productivity costs.

America's Obesity Crisis assesses the role excess weight plays in the prevalence of 23 chronic diseases and the economic consequences that result. To mention a few, obesity and overweight are linked to:

75 percent of osteoarthritis cases

64 percent of Type 2 diabetes cases

73 percent of kidney disease cases

The findings suggest that more effective weight-control strategies could reduce both the health and economic burdens of chronic diseases, according to co-author Hugh Waters, director of health economics research at the Milken Institute.

"Despite the billions of dollars spent each year on public health programs and consumer weight-loss products, the situation isn't improving," Waters said. "A new approach is needed."

The impact of obesity on chronic disease is not limited to the stress that added weight places on joints and the cardiovascular system. For example, research indicates that hormones secreted by fat cells may trigger inflammation and increase insulin resistance. These reactions can, in turn, contribute to greater risk of type 2 diabetes, cardiovascular disease, and some cancers.

Nearly 40 percent of Americans were obese and 33 percent were overweight but not obese in 2016, according to the Centers for Disease Control and Prevention. The numbers have climbed steadily since 1962, when 13 percent of the population were obese and 32 percent were overweight.

Direct medical costs include payments made by individuals, families, employers, and insurance companies to treat the diseases in question. Indirect costs include the economic impact of work absences, lost wages, and reduced productivity of patients and caregivers.

The estimates in America's Obesity Crisis are based on an analysis of data compiled by the Centers for Disease Control and Prevention, the National Center for Health Statistics, the U.S. Agency for Healthcare Research and Quality, and the Bureau of Labor Statistics. The report relies on the World Health Organization's definition of overweight as a body mass index of 25 to 29.9 and obesity as a BMI of 30 or higher.