DxCodebookFY2027 · Oct 1, 2026 – Sep 30, 2027

Category · FY2027

E66 Overweight and obesity

  • Header · not billable

E66 is not billable. The category heads 10 billable codes in FY2027, grouped under 6 subdivisions.

ICD-10 code by name

What is the ICD-10 code for obesity, unspecified?
Obesity ICD-10 code: E66.9 Obesity, unspecified. Alphabetic Index: Obesity → E66.9. Search ICD-10 for obesity
What is the ICD-10 code for morbid obesity?
Morbid obesity ICD-10 code: E66.01 Morbid (severe) obesity due to excess calories. Alphabetic Index: Obesitymorbid → E66.01. Search ICD-10 for morbid obesity
What is the ICD-10 code for overweight?
Overweight ICD-10 code: E66.3 Overweight. Search ICD-10 for overweight
What is the ICD-10 code for class 1 obesity?
Class 1 obesity ICD-10 code: E66.811 Obesity, class 1. Search ICD-10 for class 1 obesity
What is the ICD-10 code for class 3 obesity?
Class 3 obesity ICD-10 code: E66.813 Obesity, class 3. Search ICD-10 for class 3 obesity
What is the ICD-10 code for class 2 obesity?
Class 2 obesity ICD-10 code: E66.812 Obesity, class 2. Search ICD-10 for class 2 obesity
What is the ICD-10 code for severe obesity?
Severe obesity ICD-10 code: E66.01 Morbid (severe) obesity due to excess calories. Alphabetic Index: Obesitysevere → E66.01. Search ICD-10 for severe obesity

Where it sits

  1. Chapter 4 Endocrine, nutritional and metabolic diseases (E00-E89)
  2. E65-E68 Overweight, obesity and other hyperalimentation (E65-E68)
  3. E66 Overweight and obesity
Billable codes
10
Subdivisions
6
CC / MCC codes
1 / 0
HCC V28 codes
3
New FY2027
0
Index entries
23

Codes in E66

  1. E66.0
    Obesity due to excess calories
    Header
  2. E66.01
    Morbid (severe) obesity due to excess calories 1 billable code
    Billable48
  3. E66.09
    Other obesity due to excess calories 1 billable code
    Billable
  4. E66.1
    Drug-induced obesity
    Billable
    Use additional code 1

    Use additional code

    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5) T36 T50
  5. E66.2
    Morbid (severe) obesity with alveolar hypoventilation
    BillableCC48
    Inclusion terms 2

    Inclusion terms

    • Obesity hypoventilation syndrome (OHS)
    • Pickwickian syndrome
  6. E66.3
    Overweight
    Billable
  7. E66.8
    Other obesity
    Header
  8. E66.81
    Obesity class
    Header
  9. E66.811
    Obesity, class 1
    Billable
  10. E66.812
    Obesity, class 2
    Billable
  11. E66.813
    Obesity, class 3
    Billable48
  12. E66.89
    Other obesity not elsewhere classified
    Billable
  13. E66.9
    Obesity, unspecified 1 billable code
    Billable

CC/MCC: as a secondary diagnosis, unless the principal diagnosis is on the code’s PDX exclusion list (MS-DRG v44 Appendix C; list on the code card).

Sources of each column.

Instructions

At E66

Excludes2

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

Code first

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

Use additional code

  • code to identify body mass index (BMI), if known, for adults (Z68.1-Z68.45) or pediatrics (Z68.5-) Z68.1 Z68.45 Z68.5

Notes that also apply

Chapter 4 instructions (Notes 1, Excludes1 1): printed on the chapter 4 page.

Index entries

  • OHS (obesity hypoventilation syndrome) → E66.2
  • Pickwickian syndrome → E66.2
  • Overweight → E66.3
  • Obesitydrug-induced → E66.1
  • Obesitywith alveolar hypoventilation → E66.2
  • Obesityhypoventilation syndrome (OHS) → E66.2
  • Syndromealveolar hypoventilation → E66.2
  • Syndromecardiopulmonary-obesity → E66.2
  • Syndromehypoventilation, obesity (OHS) → E66.2
  • Syndromeobesity hypoventilation (OHS) → E66.2
  • SyndromePickwickian → E66.2
  • Obesityconstitutional → E66.89
  • Obesityendocrine → E66.89
  • Obesityendogenous → E66.89
  • Obesityfamilial → E66.89
  • Obesityglandular → E66.89
  • Obesityspecified type NEC → E66.89
  • Obesitydue todrug → E66.1
  • Obesityclass1 → E66.811
  • Obesityclass2 → E66.812
  • Obesityclass3 → E66.813
  • Obesitymorbidwithalveolar hypoventilation → E66.2
  • Obesitymorbidwithobesity hypoventilation syndrome (OHS) → E66.2

NCHS Alphabetic Index. Index first, then the Tabular List.

Hierarchy