Documentation and Coding Series: Obesity and Morbid Obesity

August 26, 2021

Obesity is a chronic, progressive disease. Accurately and completely coding and documenting obesity and morbid obesity can help identify and address related comorbidities that may impact our members’ overall health status.

According to the Centers for Disease Control and Prevention

  • More than 40% of U.S. adults have obesity
  • Morbid obesity, or a body mass index (BMI) of 40 or more, affects 9% of adults
  • Adults with obesity have higher risk for developing conditions including heart disease, type 2 diabetes, stroke and some types of cancer

Below is information from the ICD-10-CM Official Guidelines for Coding and Reporting 

Sample ICD-10-CM Codes for Overweight and Obesity


Morbid (severe) obesity due to excess calories


Other obesity due to excess calories


Drug-induced obesity


Morbid (severe) obesity with alveolar hypoventilation




Other obesity


Obesity, unspecified

Coding Obesity and Morbid Obesity

An obesity diagnosis is based on the clinician’s diagnostic statement that the member has the condition. An additional code should be used to identify BMI, if known.

According to ICD-10-CM guidelines, the clinician should document that the member is overweight, obese or morbidly obese. Coders must use the clinician’s statement to assign the corresponding E66 code. A coder can’t code a weight diagnosis based on BMI calculations, lab values or other measurements.

Coders should use BMI codes only when there is an associated, reportable weight diagnosis, such as obesity. A clinician other than the patient’s provider, such as a nurse or dietician, may record BMI. However, BMI shouldn’t be coded unless the clinician documents the associated weight diagnosis.

Sample ICD-10-CM Codes for BMI


BMI 20-29, adult


BMI 30-39, adult


BMI 40 or greater, adult


BMI, pediatric

BMI is a screening tool and not an indicator of health.

  • BMI adult codes are for people age 20 years and older
  •  BMI pediatric codes are for people ages 2 to 19 years
  • Don’t code BMI in pregnancy

Tips to Consider

  • Include patient demographics, such as name, date of birth and date of service in all progress notes.
  • Document legibly, clearly and concisely.
  • Ensure a credentialed provider signs and dates all documents.
  • Document how each diagnosis was monitored, evaluated, assessed and/or treated on the date of service.
  • Note complications with an appropriate treatment plan.
  • Take advantage of the Annual Health Assessment or other yearly preventative exam as an opportunity to capture conditions impacting member care.
  •  Use ICD-10 Z codes for social determinants of health  on the claims you submit to Blue Cross and Blue Shield of Illinois (BCBSIL) so we may better understand the unique, social needs of our members and help connect them with available resources.


  • ICD-10-CM Official Guidelines for Coding and Reporting, Chapter 4: Endocrine, Nutritional and Metabolic Disease (E00-E89)
  • American Hospital Association Coding Clinic  (subscription required), Fourth Quarter 2018, Body Mass Index

*E66.9 Obesity unspecified is equivalent to Obesity Not Otherwise Specified (NOS). This code should rarely be used and only when nothing else, such as the reason for obesity, is known about the disorder.

The material presented here is for informational/educational purposes only, is not intended to be medical advice or a definitive source for coding claims and is not a substitute for the independent medical judgment of a physician or other health care provider. Health care providers are encouraged to exercise their own independent medical judgment based upon their evaluation of their patients’ conditions and all available information, and to submit claims using the most appropriate code(s) based upon the medical record documentation and coding guidelines and reference materials. References to other third-party sources or organizations are not a representation, warranty or endorsement of such organization. Any questions regarding those organizations should be addressed to them directly.