Americans continue to struggle with obesity, and new research confirms how much the numbers have grown over the past two decades. A study published online today in JAMA Internal Medicine finds that more than two-thirds of Americans are either overweight or obese, estimates on par with recent figures from the Centers for Disease Control and Prevention.

For the study, researchers from the Washington University School of Medicine analyzed data from the National Health and Nutrition Examination Survey from 2007 to 2012 to estimate the prevalence of overweight and obesity. Participants included 15,208 men and women age 25 or older.

The results, reported in a research letter, found that nearly 75 percent of men and 67 percent of women are overweight or obese. This is a significant increase over the past 20 years; a similar study using data from 1988-1994 estimated that 63 percent of men and 55 percent of women were overweight or obese at that time.

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In the latest study, the group that showed the greatest increase in the most obese weight category was non-Hispanic black women.

Obesity has been linked to a number of serious health problems, from heart disease and diabetes to sleep apnea and depression, and even an increased risk of death.

"This generation is not going to outlive its predecessor, and that's pretty amazing," Dr. Mitchell Roslin of Lenox Hill Hospital in New York told CBS News.

Roslin, an obesity surgeon who was not involved in the study, says he sees evidence of patients needing surgical intervention for extreme weight problems at younger and younger ages. If things don't change, he said, "obesity is going to pass cigarette smoking as the leading cause of cancer deaths in the U.S."

"We see this as a wake-up call to implement policies and practices designed to combat overweight and obesity, to implement what we already know into place to accelerate the obesity prevention and treatment," study author Lin Yang, post-doctoral researcher in the Division of Public Health Sciences at Washington University School of Medicine, told CBS News. "Population-based strategies may help to alter the obesity trend through physical environment interventions, enhancing primary care efforts, and shifting society norms of behavior."

Yang suggested efforts be made in the form of individual and policy changes, such as adding bike lanes and more pedestrian-friendly areas in cities to encourage more physical activity in daily life. She also suggested making the work environment a less sedentary place by using the stairs instead of the elevator, for example.

As for the role of diet, "We also know food choice and consumption contribute greatly to excess intake and then overweight and obesity," she said. "Not everyone has accessibility to affordable, healthy food. This needs to be addressed on a national and then local level."