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 2026, 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.
Body Mass Index
An indicator of body density as determined by the relationship of BODY WEIGHT to BODY HEIGHT. BMI=weight (kg)/height squared (m2). BMI correlates with body fat (ADIPOSE TISSUE). Their relationship varies with age and gender. For adults, BMI falls into these categories: below 18.5 (underweight); 18.5-24.9 (normal); 25.0-29.9 (overweight); 30.0 and above (obese). (National Center for Health Statistics, Centers for Disease Control and Prevention)
Choroideremia
An X chromosome-linked abnormality characterized by atrophy of the choroid and degeneration of the retinal pigment epithelium causing night blindness.
Diabesity
Co-occurrence of DIABETES MELLITUS and OBESITY largely due to diabetic complication from HYPERGLYCEMIA. Diabesity is also associated with faster deterioration of diabetic symptoms and complications.
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.
Obesity Management
An integrated professional approach to screening, evaluation, control, and reduction of abnormal WEIGHT GAIN.
Obesity Paradox
An observation that high BODY MASS INDEX is sometimes associated with lower CARDIOVASCULAR DISEASE mortality in certain population, e.g., ELDERLY.
Obesity, Abdominal
A condition of having excess fat in the abdomen. Abdominal obesity is typically defined as waist circumferences of 40 inches or more in men and 35 inches or more in women. Abdominal obesity raises the risk of developing disorders, such as DIABETES; HYPERTENSION; and METABOLIC SYNDROME.
Obesity, Metabolically Benign
A sub-PHENOTYPE of obese individuals who have a risk for CARDIOVASCULAR DISEASES between that of healthy individuals with normal weight and unhealthy individuals with obesity.
Obesity, Morbid
The condition of weighing two, three, or more times the ideal weight, so called because it is associated with many serious and life-threatening disorders. In the BODY MASS INDEX, morbid obesity is defined as having a BMI greater than 40.0 kg/m2.
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.
Pediatric Obesity
BODY MASS INDEX in children (ages 2-12) and in adolescents (ages 13-18) that is grossly above the recommended cut-off for a specific age and sex. For infants less than 2 years of age, obesity is determined based on standard weight-for-length percentile measures.
Pregnancy in Obesity
BODY MASS INDEX in PREGNANT PEOPLE that is excessively above the recommended cut-off.
Weight Gain
Increase in BODY WEIGHT over existing weight.
Weight Prejudice
Negative attitudes towards and beliefs about others because of their weight. These negative attitudes are manifested by stereotypes and/or prejudice towards people with weight over or under a cultural norm.
About the E66 Code Range
The ICD-10 codes in the E66 category are used to accurately identify and classify various forms of overweight and obesity, including specific causes, severity levels, and related conditions. These codes help differentiate between general overweight, obesity due to excess calories, drug-induced obesity, and more complex obesity types with complications.
These codes range from E66.0 for obesity due to excess calories to E66.9 for unspecified obesity. Notably, E66.01 addresses severe or morbid obesity, known by synonyms such as morbid obesity and obese class III, while E66.1 covers drug-induced obesity. The spectrum includes overweight as defined by body mass index ranges under E66.3. Complex or genetic-related obesity cases fall under codes like E66.89, which includes diverse obesity types, such as central or syndromic obesity, with many synonyms aiding in precise coding. This range assists healthcare professionals and coders in selecting the exact ICD-10 code for conditions like morbid obesity, drug-induced obesity, and childhood overweight, facilitating targeted healthcare management and documentation.
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, 2025 through September 30, 2026. 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 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
