NHANES August 2021–August 2023 Data Released with Obesity Report

CDC’s National Center for Health Statistics recently released its first wave of data files from the August 2021-August 2023 cycle of the National Health And Nutrition Examination Survey (NHANES). NCHS also published the first report analyzing these data. The report, Obesity and Severe Obesity Prevalence in Adults: United States, August 2021–August 2023, describes recent trends in adult obesity and differences in obesity by sex, age, and education level.

The report highlighted that more than 4 in 10 adults had obesity and almost 1 in 10 adults had severe obesity during August 2021–August 2023.

“Obesity prevalence among U.S. adults did not increase during the past 10 years, but severe obesity prevalence did increase,” said Samuel Emmerich, lead author of the report. “Some reports have found that obesity increased during the [COVID-19] pandemic, but we found that obesity did not change significantly from before to after the pandemic.”

NHANES measures health and nutrition in the U.S. civilian, noninstitutionalized population. Civilians are people not serving on active duty in the military. Institutionalized people live in places like correctional facilities, skilled-nursing homes, and mental (psychiatric) hospitals.

Unique for national surveys, NHANES not only includes interviews but also collects actual measurements through a health exam and lab work. By taking actual measurements in addition to collecting self-reported information, NHANES ensures the collection of accurate health data.

“Measuring height and weight to estimate obesity prevalence is very important, as estimates based on self-reported height and weight are underestimates because people tend to underestimate their weight and overestimate their height,” noted Emmerich.

NHANES data include many topics in addition to obesity. The NHANES August 2021–August 2023 files contain data and documentation for the interview, laboratory, and exam portions of the survey. Some of the topics include:

Interview data

• COVID-19
• Diabetes
• Diet behavior and nutrition
• Physical activity and physical fitness

Laboratory data

• Heavy metals
• Cholesterol
• Iron
• Pesticides

Exam data

• Balance
• Body measurements
• Blood pressure

The August 2021–August 2023 nationally representative data files are based on an updated sample design and modified questionnaires and examination procedures. The public release of files consists of:

• 61 files, including demographic variables and sample weights
• 3 examination files
• 19 laboratory files
• 38 questionnaire files

In addition to the public use files, online overview and analytic guidance documents accompany the release. These resources provide guidance on the proper use of the data.

NHANES is conducted in 2-year cycles. After suspension of NHANES field operations in March 2020 due to the COVID-19 pandemic, data collection began for a new 2-year cycle in August 2021.

NHANES is starting the next 2-year data collection cycle in early 2025. New data will be released after that data collection cycle is complete.