Obesity ICD-10 code
The ICD-10-CM code for obesity is E66.9 (obesity, unspecified). It is billable and valid for submission on a claim. There are 14 related codes, and which one you use depends on what the documentation supports.
Also written as morbid obesity, bmi.
The mistake coders make here
E66.01 is morbid (severe) obesity due to excess calories. Obesity codes carry a 'use additional code' instruction for the BMI (Z68.-), and payers frequently look for it.
Putting obesity on a claim? Check the claim’s diagnosis codes free: Excludes1 conflicts, header codes and missing seventh characters, before it goes out.
ICD-10-CM codes for obesity
10 of 14 are billable. Green means you can submit it as-is.
| Code | Use it when |
|---|---|
| E66.9 | Obesity, unspecified |
| E66.01 | Morbid (severe) obesity due to excess calories |
| E66.09 | Other obesity due to excess calories |
| E66.3 | Overweight |
| E66 | Overweight and obesitynot billable on its own |
| E66.8 | Other obesitynot billable on its own |
| E66.81 | Obesity classnot billable on its own |
| E66.811 | Obesity, class 1 |
| E66.812 | Obesity, class 2 |
| E66.813 | Obesity, class 3 |
| E66.89 | Other obesity not elsewhere classified |
| E66.1 | Drug-induced obesity |
| E66.0 | Obesity due to excess caloriesnot billable on its own |
| E66.2 | Morbid (severe) obesity with alveolar hypoventilation |
Once you have the code
- Check the whole claim: Excludes1 conflicts and missing seventh characters, free
- Denial codes explained: what CO-16, CO-97 and the rest actually mean
- Decision guides: walk a chart note to a code, guideline cited
- Everything here that is free, and the one thing no free tool includes
The obesity code needs a cause or a class; the BMI needs the obesity code
E66.9 is obesity unspecified. E66.01 is morbid (severe) obesity due to excess calories: the words 'morbid', 'severe' or 'class 3' in the note support it; E66.09 is other obesity due to excess calories; E66.1 is drug-induced obesity; E66.2 is morbid obesity with alveolar hypoventilation; E66.3 is overweight. FY2025 added E66.81- for obesity by class as the provider documents it: E66.811 class 1, E66.812 class 2, E66.813 class 3, with E66.89 for other obesity. A BMI code from Z68.- is reported alongside the obesity or overweight diagnosis, never on its own as the diagnosis.
Who may document what: Guideline I.B.14
The BMI itself can be taken from documentation by a clinician who is not the patient's provider, a dietitian's note or nursing intake, but the associated diagnosis (obesity, overweight, morbid obesity) must be documented by the provider. A BMI of 42 in the vitals with no provider diagnosis does not support E66.01 or Z68.41; it supports a query. Z68.41 through Z68.45 are BMI 40 and over in adults, in five-unit bands; Z68.30-Z68.39 are 30 to 39.9; pediatric BMI is coded by percentile in Z68.5-.
Obesity as a comorbidity, and in pregnancy
Obesity is reported whenever it affects the care (anaesthesia risk, wound healing, drug dosing, the indication for a bariatric procedure) and the class matters for risk adjustment, so E66.9 with a Z68.4- code is a weaker record than E66.01 or E66.813 with the same BMI. Obesity complicating pregnancy is O99.21- first with the E66.- code and the Z68 code following. Bariatric surgery status after the fact is Z98.84, and the encounter for weight management counselling is Z71.3.
Common questions
- What is the ICD-10 code for morbid obesity?
- E66.01, morbid (severe) obesity due to excess calories, with a Z68.4- code for the BMI when it is documented (Z68.41 for BMI 40.0-44.9, Z68.42 for 45.0-49.9, and so on). Since FY2025, E66.813 (obesity class 3) is available when the provider documents the class.
- Can I code a BMI without an obesity diagnosis?
- No. Per Guideline I.B.14 the Z68 BMI code is reported only with an associated weight diagnosis documented by the provider, such as E66.- or E66.3 for overweight.
- What is the ICD-10 code for overweight?
- E66.3, overweight, with the Z68 code for the BMI (Z68.25-Z68.29 for BMI 25.0-29.9).