E66.01 Morbid (severe) obesity due to excess calories

The ICD-10-CM code for Morbid (severe) obesity due to excess calories is E66.01 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

4: Endocrine, nutritional and metabolic diseases (E00-E89)

Section

E65-E68: Overweight, obesity and other hyperalimentation (E65-E68)

Category E66

14 codes (10 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to E66.01:

• Obesity › morbid
• Obesity › severe
• Obesity › morbid › due to excess calories
• Obesity › due to › excess calories › morbid
• Obesity › due to › excess calories › severe

U.S. Hospital Utilization

• An estimated 2,224,875 U.S. inpatient stays in 2023 included E66.01 among the documented diagnoses.
• 189,675 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

Diabetes mellitus (TOC entry)

a. Diabetes mellitus ................................................................................................................... 39

Obesity (TOC entry)

b. Obesity .................................................................................................................................. 42

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)