In case you missed it: New ICD-10-CM codes for obesity classes

As of Oct. 1, 2024, the ICD-10-CM code updates have introduced new codes to describe the classes of obesity. These new codes are:

• E66.811: Obesity, class 1
• E66.812: Obesity, class 2
• E66.813: Obesity, class 3

According to the Centers for Disease Control and Prevention (CDC), the adult BMI classifications for these obesity classes are as follows:

• Class 1 Obesity: BMI of 30 to less than 35
• Class 2 Obesity: BMI of 35 to less than 40
• Class 3 Obesity: BMI of 40 or greater

Obesity is recognized as a chronic disease characterized by an excessive accumulation of body fat. The body mass index (BMI) is the standard measure used to categorize obesity. Previously, ICD-10-CM classifications included overweight, obese or morbidly obese. The addition of specific obesity classes will enhance the study and tracking of this disease. Obesity not only increases the risk of serious conditions such as heart disease, diabetes, and respiratory issues but also contributes to social stigma, depression, and low self-esteem.

Important updates for coders and clinicians 

Heads up #1: In the second quarter of 2022, Coding Clinic advised capturing the diagnosis of Class 3 Obesity as E66.01, Morbid (severe) obesity due to excess calories. Class 1 and Class 2 required clarification from the provider. With the new codes, you should now code the specific class to the correct and most specific ICD-10-CM code. Note that for HCC risk adjustment coders, the new E66.811, Obesity, Class 1 and E66.812, Obesity, Class 2 codes do not risk adjust to a payment model, unlike E66.01, Morbid obesity and E66.813, Obesity, Class 3. This change may significantly impact coding practices if providers frequently document Class 1 or Class 2 obesity as severe, as you will no longer code “severe” obesity to E66.01 in 2025.

Heads up #2: Clinical terminology can be confusing. “Severe obesity” is often used synonymously with both Class 3 obesity and morbid obesity. To complicate matters further, the BMI index for Class 3 obesity starts at 40 kg/m²*, the same as for morbid obesity. The key takeaway is that when Class 3 obesity is documented, coders should assign the new E66.813, Obesity, Class 3. When “severe” obesity is documented without further specificity, coders should index and assign E66.01, Morbid (severe) obesity. As of April 1, 2025, the Official Coding Guidelines have been updated that if both “Class 3 obesity and morbid obesity are documented, only a code for Class 3 obesity should be assigned as it is more specific.”.

Action steps for providers 

To avoid confusion and ensure accurate coding, it is crucial to educate providers about these changes. Providers need to understand the importance of precise documentation and the differences in coding Class 3 obesity and morbid obesity so that coders can assign the most accurate code representing the provider's diagnosis of the patient’s condition. Early education and clear communication will help streamline the coding process and improve the accuracy of obesity-related diagnoses.
 

*BMI reference can be found at CDC.gov Centers for Disease Control and Prevention and NIH.gov National Institute for Health.

Will Morriss, CCS, CCDS-O, is a senior coding analyst at Solventum.
Diane Pittman, CPC, CRC, CPMA, CCDS-O, is a senior clinical analyst at Solventum.