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title: "ICD-10-CM E66.01: Morbid (severe) obesity due to excess… | BillingBrief"
description: "ICD-10-CM code E66.01: Morbid (severe) obesity due to excess calories. Category, related codes, and the official source, in plain English."
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# E66.01 Morbid (severe) obesity due to excess calories

ICD-10-CM · [CMS code reference](#source)

**Official ICD-10-CM description:** Morbid (severe) obesity due to excess calories

## Coding notes

From the ICD-10-CM FY2027 (effective October 1, 2026) tabular list. Notes on a parent code or category apply here too.

### Excludes1

Not coded together with this code. The exception is when the two conditions are unrelated to each other.

-   morbid (severe) obesity with alveolar hypoventilation ([E66.2](https://billingbrief.com/icd10/e66.2/))

### Excludes2

Not part of this code, but both can be coded when both are documented.

-   adiposogenital dystrophy (E23.6)
-   lipomatosis dolorosa \[Dercum\] (E88.2)
-   lipomatosis NOS (E88.2)
-   Prader-Willi syndrome (Q87.11)

### Code first

Code the underlying condition first, then this code.

-   obesity complicating pregnancy, childbirth and the puerperium, if applicable (O99.21-)

### Use additional code

Add a second code for the following, when documented.

-   code to identify body mass index (BMI), if known, for adults (Z68.1-[Z68.45](https://billingbrief.com/icd10/z68.45/)) or pediatrics (Z68.5-)

## Related codes

-   [`E66.09` Other obesity due to excess calories ICD-10-CM](https://billingbrief.com/icd10/e66.09/)
-   [`E66.1` Drug-induced obesity ICD-10-CM](https://billingbrief.com/icd10/e66.1/)
-   [`E66.2` Morbid (severe) obesity with alveolar hypoventilation ICD-10-CM](https://billingbrief.com/icd10/e66.2/)
-   [`E66.3` Overweight ICD-10-CM](https://billingbrief.com/icd10/e66.3/)
-   [`E66.811` Obesity, class 1 ICD-10-CM](https://billingbrief.com/icd10/e66.811/)
-   [`E66.812` Obesity, class 2 ICD-10-CM](https://billingbrief.com/icd10/e66.812/)
-   [`E66.813` Obesity, class 3 ICD-10-CM](https://billingbrief.com/icd10/e66.813/)
-   [`E66.89` Other obesity not elsewhere classified ICD-10-CM](https://billingbrief.com/icd10/e66.89/)

## Common questions

### Is E66.01 a billable code?

Yes. E66.01 is a billable ICD-10-CM code in the ICD-10-CM FY2027 (effective October 1, 2026) code set.

## From the source

Official description from [CMS](https://www.cms.gov/medicare/coding-billing/icd-10-codes).
ICD-10-CM FY2027 (effective October 1, 2026).

Code set

ICD-10-CM

Category

E66 Overweight and obesity

Chapter

Endocrine, nutritional and metabolic diseases

Billable

Yes

Educational reference only. Not medical, legal, or billing advice. Always check the current official code set and payer policy before you bill. [About BillingBrief and our sources](https://billingbrief.com/about/).