Index to Diseases entry: Obesity
Each row is a subterm under the entry. Indented rows refine the row above; “see” sends you to another entry. Look the code up in the tabular list before reporting it: the tabular notes can require a more specific or an additional code.
| Documentation | Code | Code description or cross-reference |
|---|---|---|
| with alveolar hypoventilation | E66.2 | Morbid (severe) obesity with alveolar hypoventilation |
| adrenal | E27.8 | Other specified disorders of adrenal gland |
| class | — | |
| 1 | E66.811 | Obesity, class 1 |
| 2 | E66.812 | Obesity, class 2 |
| 3 | E66.813 | Obesity, class 3 |
| complicating | — | |
| childbirth | O99.214 | Obesity complicating childbirth |
| pregnancy | O99.21- | Obesity complicating pregnancy, childbirth, and the puerperium |
| puerperium | O99.215 | Obesity complicating the puerperium |
| constitutional | E66.89 | Other obesity not elsewhere classified |
| dietary counseling and surveillance | Z71.3 | Dietary counseling and surveillance |
| drug-induced | E66.1 | Drug-induced obesity |
| due to | — | |
| disruption of MC4R pathway | E88.82 | Obesity due to disruption of MC4R pathway |
| drug | E66.1 | Drug-induced obesity |
| excess calories | E66.09 | Other obesity due to excess calories |
| gene mutation | — | |
| endocrine | E66.89 | Other obesity not elsewhere classified |
| endogenous | E66.89 | Other obesity not elsewhere classified |
| exogenous | E66.09 | Other obesity due to excess calories |
| familial | E66.89 | Other obesity not elsewhere classified |
| glandular | E66.89 | Other obesity not elsewhere classified |
| hypothyroid | — | see Hypothyroidism |
| hypoventilation syndrome(OHS) | E66.2 | Morbid (severe) obesity with alveolar hypoventilation |
| morbid | E66.01 | Morbid (severe) obesity due to excess calories |
| with | — | |
| due to excess calories | E66.01 | Morbid (severe) obesity due to excess calories |
| nutritional | E66.09 | Other obesity due to excess calories |
| pituitary | E23.6 | Other disorders of pituitary gland |
| severe | E66.01 | Morbid (severe) obesity due to excess calories |
| specified type NEC | E66.89 | Other obesity not elsewhere classified |
Tabular list notes for E66.9
- Inclusion terms
- Obesity NOS
How to read an Index to Diseases entry
- Words in parentheses after a term are nonessential modifiers: they may or may not appear in the record, and they do not change the code.
- Indented subterms are essential modifiers. Each one describes a different site, type or cause, and when the record supports it, the subterm's code replaces the default code.
- “With” and “in” link two conditions. The Official Guidelines presume a causal relationship between conditions linked by “with” in the index unless the provider documents that they are unrelated.
- “See” sends you to another entry that holds the code; “see also” points to another entry that may be useful.
- A code that ends in a dash, such as I50.-, is incomplete: the tabular list gives the characters it still needs.
- Never report a code from the index alone. Find it in the tabular list and apply its includes, excludes, code first, use additional code and 7th-character instructions before you report it.
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Frequently asked questions
What is the ICD-10 code for obesity?
E66.9 (Obesity, unspecified) is the code the index assigns to "Obesity" with no further detail. Confirm it in the tabular list before reporting it, because the tabular notes can require a different or additional code.
Which documentation changes the code for obesity?
The index lists 26 subterms with their own codes, including with alveolar hypoventilation (E66.2); adrenal (E27.8); class 1 (E66.811); class 2 (E66.812); class 3 (E66.813).
Sources
Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-10. Verify against the primary file before billing or contracting decisions. The reference methodology explains how each figure is computed from these files.
- ICD-10-CM FY2027 tabular order file (category titles)Version FY2027 · effective 2026-10-01 · file icd10cm_order_2027.txtSHA-256 38981fb2c1226e2b…
- ICD-10-CM FY2027 tabular list (chapter titles and ranges)Version FY2027 · effective 2026-10-01 · file 2027-code-tables-tabular-index.zipSHA-256 37baa476323714be…
- ICD-10-CM FY2027 code descriptions addenda (codes added, deleted and revised)Version FY2027 · effective 2026-10-01 · file icd10cm_codes_addenda_2027.txtSHA-256 cfba025073235af4…
Disclaimer
The entry, subterms and codes are reproduced from the FY2027 ICD-10-CM index; code descriptions are from the FY2027 code files. Code from the medical record using both the index and the tabular list, under the ICD-10-CM Official Guidelines. Not legal, clinical or billing advice.
Found a figure that does not match the CMS file? Report a data correction with the CMS file and the value you expected; the request reaches the editorial team through the contact form.