It's the new normal: Two out of three Americans are fat - and the nation's waistline is getting bigger all the time, according to a new analysis.

More than two-thirds of women and three-fourths of men in the United States are now either overweight or clinically obese, according to a new study, Live Science reports.

The study, published in the journal JAMA Internal Medicine, tracked data gathered from the long-running National Health and Nutrition Examination Survey, which included more than 15,000 men and women age 25 and older, from 2007 to 2012. The results indicated nearly 40 percent of men and nearly 30 percent of women were overweight, and about 35 percent of men and nearly 37 percent of women were obese.

Participants were classified as overweight if their body mass index (BMI) was between 25 and 29.9, and obese if their BMI was 30 or higher.

When compared with an analysis conducted nearly 20 years before this study, the results show that more people are now overweight and obese, said

Lead researcher Lin Yang, an epidemiologist at Washington University School of Medicine in St. Louis, said prior estimates — based on NHANES data gathered between 1988 and 1994 — indicated 63 percent of men and 55 percent of women age 25 and older were overweight or obese.

Yang called the findings a wake-up call on weight gain and obesity, which burden the American healthcare system and society.

"Overweight and obesity are associated with several chronic conditions, including hypertension, heart disease, Type 2 diabetes, osteoarthritis, and some cancers," she said. "A collaborative effort must be made across the board to stop this trend that is compromising and shortening the lives of many."