"Mean (or average) weight, waist circumference, and BMI in adults 20 years and older increased between 1999-2000 and 2015-2016," Cynthia Ogden, one of the report's authors and an epidemiologist at the US Centers for Disease Control and Prevention's National Center for Health Statistics, wrote in an email.
The report looked at the height, weight, body-mass index and waist circumference of American adults; it updated a 2004 report on these trends between 1960 and 2002.
In that previous study period, "mean (or average) weight increased by more than 24 pounds and mean height increased by [about] 1 inch," Ogden said.
The new report shows the trend continuing in weight but not in height.
The average weight of American men in 2015-16 was 197.9 pounds; for women, it was 170.6 pounds. This is up from 189.4 pounds and 163.8 pounds, respectively, in 1999-2000.
Black men, Mexican-American women and Asian men and women were the only groups in the report that did not show a significant increase in weight over that period.
BMI, a formula involving height and weight , also increased. In 2015-16, the average BMI was 29.1 for men and 29.6 for women. Both numbers have increased since 1999-2000 when they were 27.8 in men and 28.2 in women.
Americans' average BMI "is now almost 30 which is the cutoff for obesity," Ogden noted. According to the CDC, a normal or healthy BMI is between 18.5 and 24.9. A BMI of 25 to 29.9 is considered overweight.
Average waist circumference also increased more than 1 inch in men and 2 inches in women, Ogden said: from 99.1 centimeters (39 inches) in men in 1999-2000 to 102.1 centimeters (40.2 inches) in 2015-16. For women, the measurement went from 92.2 centimeters (36.3 inches) to 98 centimeters (38.6 inches).
While weight is going up, height is going down. According to the new report, the overall average height for women decreased slightly from 162.1 centimeters (5 feet, 3.8 inches) in 1999-2000 to 161.7 centimeters (5 feet, 3.7 inches) in 2015-16.
For men, the average height in 1999-2000 was 175.6 centimeters (5 feet, 9.2 inches). It increased until 2003-04, when the average height was 176.4 centimeters (5 feet, 9.4 inches), and then decreased again until 2015-16, when it was 175.4 centimeters (5 feet, 9.1 inches).
The report uses data from 47,233 Americans over the age of 20, gathered from the National Health and Nutrition Examination Surveys from 1999 to 2016.
Ogden noted that for weight, waist circumference and BMI, the "biggest increases between 1999-2000 and 2015-2016 were in Mexican American adults."
For Mexican-American women, average body weight did not start changing until the 2009-10 period, and then it jumped from 161.6 pounds to 172 pounds in 2015-16, according to the report.
Michael Long , an assistant professor of prevention and community health at George Washington University, wrote in an email that "By focusing on changes in average BMI, this study shows that the problem of excess weight gain is impacting everyone, not just the 4 out of 10 adults with obesity. On average, we are all getting heavier."
Long, who was not involved in the research, pointed out that this weight gain increases the risk of chronic diseases such as diabetes and that "providing excellent healthcare to people with obesity is critical."
Rising weight across the country carries risks to more than just individual health, according to Dr. Jennifer Kraschnewski, an associate professor of medicine, pediatrics and public health sciences at the Penn State University College of Medicine .
"Medical costs to care for patients with obesity are estimated to be as high as $210 billion per year. In addition, obesity is associated with job absenteeism and lower productivity while at work, costing the system more than $6 billion each year," Kraschnewski, who was not involved with this research, wrote in an email.
Kraschnewski believes that there are a number of reasons for rising obesity, such as increasingly unhealthy diets, and thus there are a number of ways in which it should be addressed.
"The complexity of the many causes of obesity require that any solution be equally complex," she said, citing community and policy approaches such as soda taxes.