Overweight and obesity (E66) ICD-10-CM
The E66 code range covers overweight and obesity with 14 ICD-10-CM diagnosis codes. 10 of them are billable and valid for claim submission in fiscal year 2027, and the category headers group them but cannot themselves be billed.
Code First
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.
- obesity complicating pregnancy, childbirth and the puerperium, if applicable O99.21
Use Additional Code
The “use additional code” indicates that a secondary code could be used to further specify the patient’s condition. This note is not mandatory and is only used if enough information is available to assign an additional code.
Type 2 Excludes
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
Codes in the E66 Range 14 codes · 10 billable
- E66 Overweight and obesityNon-billable
- E66.0 Obesity due to excess caloriesNon-billable
- E66.01 Morbid (severe) obesity due to excess calories
- E66.09 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 obesityNon-billable
- E66.81 Obesity classNon-billable
- E66.811 Obesity, class 1
- E66.812 Obesity, class 2
- E66.813 Obesity, class 3
- E66.89 Other obesity not elsewhere classified
- E66.9 Obesity, unspecified
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the E66 range.
Obesity
A status with BODY WEIGHT that is grossly above the recommended standards, usually due to accumulation of excess FATS in the body. The standards may vary with age, sex, genetic or cultural background. In the BODY MASS INDEX, a BMI greater than 30.0 kg/m2 is considered obese, and a BMI greater than 40.0 kg/m2 is considered morbidly obese (MORBID OBESITY).
Obesity Hypoventilation Syndrome
HYPOVENTILATION syndrome in very obese persons with excessive ADIPOSE TISSUE around the ABDOMEN and DIAPHRAGM. It is characterized by diminished to absent ventilatory chemoresponsiveness; chronic HYPOXIA; HYPERCAPNIA; POLYCYTHEMIA; and long periods of sleep during day and night (HYPERSOMNOLENCE). It is a condition often related to OBSTRUCTIVE SLEEP APNEA but can occur separately.
Overweight
A status with BODY WEIGHT that is above certain standards. In the scale of BODY MASS INDEX, overweight is defined as having a BMI of 25.0-29.9 kg/m2. Overweight may or may not be due to increases in body fat (ADIPOSE TISSUE), hence overweight does not equal over fat.
About the E66 Code Range
Overweight has its own entry. Obesity is divided by cause, severity, class, and other descriptions.
E66.0 identifies obesity due to excess calories and separates severe obesity from other obesity due to excess calories. E66.1 identifies drug-induced obesity. E66.2 identifies severe obesity with reduced breathing in the lungs' air sacs. E66.3 identifies overweight.
E66.8 contains other obesity, including E66.81, which splits obesity into classes 1, 2, and 3. E66.9 identifies obesity without a specified type.
Questions About This Page
How many billable codes are in the E66 range?
Of the 14 codes in this range, 10 are billable and valid for claim submission from October 1, 2026 through September 30, 2027. Category header codes group them but cannot be reported on claims.
What does the E66 range classify?
The range classifies overweight and obesity. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2027 ICD-10-CM Tabular List and order file, effective October 1, 2026 through September 30, 2027.
