Coding Tip: Morbid Obesity

November 1, 2022
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HCC Best Practice: Identifying and Coding Morbid Obesity

OHN is dedicated to providing the knowledge, resources, processes and technology you need for success in value-based care so you can do more of what you love – taking care of patients. In the months to come, we’ll share one coding tip and highlight one best practice advisory (BPA) each month to help to support your clinical documentation efforts.

Additionally, the clinical documentation excellence (CDE) team is here to support you – email with any questions.


The NIH definition of morbid obesity:

  • Being 100 pounds or more above ideal body weight; or
  • Having a BMI of 40 or greater; or
  • Having a BMI of 35 or greater and one or more comorbid conditions:
  • High blood pressure and hypertension
  • High cholesterol and triglycerides
  • Type2 diabetes mellitus
  • Metabolic syndrome
  • Heart disease
  • Stroke
  • Kidney disease
  • Sleep apnea
  • Cancer
  • Fatty liver disease
  • Gallbladder disease
  • Osteoarthritis

How to code & document


  • Document the presence or absence of any current symptoms related to obesity, morbid obesity, overweight, etc.


  • Document the patient’s height, weight and BMI. (The medical coder is not allowed to use the patient’s documented height and weight to calculate the BMI and assign a corresponding ICD-10-CM code. Rather, the healthcare provider must specifically document the BMI in the medical record.)
  • In the physical exam, describe to the highest specificity any current associated observations (such as overweight, obese, morbidly obese, etc.).

Final assessment/impression

  • Specificity: Document the overweight or obesity diagnosis to the highest level of specificity, as in “morbid obesity”, “severe obesity”, “obesity due to excess calories”, etc.
  • Abbreviations: Limit or avoid altogether the use of abbreviations or acronyms. Best practice is to spell out each final diagnosis in full.
  • Associated conditions: Document clear linkage between underlying conditions that caused the overweight or obesity condition and between the BMI and other diagnoses for which the BMI has clinical significance.
  • Current versus historical: Do not describe a current obesity diagnosis as “history of.” In diagnosis coding, the phrase “history of” means the condition is historical and no longer exists as a current problem.

In summary

  • Physicians use multiple resources and criteria to define and diagnose obesity-related conditions.
  • BMI is a screening tool only. It is not the only criterion used to diagnose obesity/morbid obesity.
  • Diagnosis code assignment is based on the physician’s clinical judgment and corresponding medical record description of the specific obesity condition.

Coding obesity

1) Overweight and obesity classify to subcategory E66:

  • E66.Ø-Obesity due to excess calories
  • E66.Ø1 Morbid(severe) obesity due to excess calories
  • E66.Ø9 Other obesity due to excess calories
  • E66.1 Drug-induced obesity
  • E66.2 Morbid (severe) obesity with alveolar hypoventilation
  • E66.3 Overweight
  • E66.8 Other obesity
  • E66.9 Obesity, unspecified
  • Use an additional code to identify BMI if known (Z68).

2) Individuals who are overweight, obese, morbidly obese, etc., are at risk for certain medical conditions when compared to persons of normal weight. Therefore, these diagnoses always are clinically significant and reportable when they are documented and supported in the medical record as current conditions.

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