2026 ICD-10-CM Diagnosis Code E66.9Obesity, unspecified
ICD-10-CM Codes›E00–E89›E65-E68›E66
- Billable — Valid for Submission
- Chronic Condition
E66.9 is a billable ICD-10-CM diagnosis code for obesity, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 640 through 641. The code is flagged as a questionable admission, since it rarely justifies inpatient admission on its own. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Obesity.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for E66.9.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Benign intracranial hypertension
- Blood magnesium below reference range
- Blood magnesium outside reference range
- Body mass index 30+ - obesity
- Central obesity
- Choroideremia
- Choroideremia with deafness and obesity syndrome
- Cognitive impairment, coarse facies, heart defects, obesity, pulmonary involvement, short stature, skeletal dysplasia syndrome
- Colobomatous microphthalmia
- Colobomatous microphthalmia, obesity, hypogenitalism, intellectual disability syndrome
- Congenital mixed conductive and sensorineural hearing loss
- Deafness, encephaloneuropathy, obesity, valvulopathy syndrome
- Difficulty maintaining weight loss
- Excess subcutaneous fat
- Fetal disorder due to maternal obesity
- Fetal disorder due to maternal obesity with adult body mass index 30 or greater but less than 40
- Fetal disorder due to maternal obesity with adult body mass index equal to or greater than 40
- Generalized obesity
- Genetic syndromic childhood obesity
- Has seen dietitian - obesity
- Hereditary choroidal dystrophy
- Impaired glucose tolerance in obese
- Increased body mass index
- Intellectual disability, obesity, brain malformation, facial dysmorphism syndrome
- Intellectual disability, obesity, prognathism, eye and skin anomalies syndrome
- Intellectual disability, seizures, macrocephaly, obesity syndrome
- Lifelong obesity
- Lower body obesity
- Lymphedema associated with obesity
- Mixed conductive AND sensorineural hearing loss
- MOMO syndrome
- Myelopathy due to obesity
- MYT1L-related developmental delay, intellectual disability, obesity syndrome
- Neurological disorder due to obesity
- Neuropathy due to obesity
- Obese
- Obese build
- Obese class I
- Obese class II
- Obesity
- Obesity associated disorder
- Obesity by adipocyte growth pattern
- Obesity by contributing factors
- Obesity by fat distribution pattern
- Obesity due to leptin receptor gene deficiency
- Obesity in adolescence
- Obesity in mother complicating childbirth
- Obesity monitoring check done
- Obesity monitoring default
- Obesity monitoring deleted
- Obesity monitoring status
- Peripheral neuropathy due to obesity
- PHIP-related behavioral problems, intellectual disability, obesity, dysmorphic features syndrome
- Primary hypomagnesemia, generalized seizures, intellectual disability, obesity syndrome
- Pseudoneoplasm cerebri due to obesity
- Reason for obesity therapy - occupational
- Seen by dietitian
- Sees or has seen dietician
- Severe obesity
- Simple obesity
- Skin striae
- Skin striae due to obesity
- Spastic paraplegia, intellectual disability, nystagmus, obesity syndrome
- Treatment of obesity changed
- Treatment of obesity started
- Type 2 diabetes mellitus in obese
- Understands reducing diet
- X-linked intellectual disability, hypogonadism, ichthyosis, obesity, short stature syndrome
- X-linked sensorineural hearing loss
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Obesity NOS
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
- Obesity - E66.9
External Cause of Injuries IndexGuidance
References for this code in the External Cause of Injuries Index.
- Obesity
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Diabesity
co-occurrence of diabetes mellitus and obesity largely due to diabetic complication from hyperglycemia. diabesity is also associated with faster deterioration of diabetic symptoms and complications.Obesity
a status with body weight that is grossly above the recommended standards, usually due to accumulation of excess fats in the body. the standards may vary with age, sex, genetic or cultural background. in the body mass index, a bmi greater than 30.0 kg/m2 is considered obese, and a bmi greater than 40.0 kg/m2 is considered morbidly obese (morbid obesity).Obesity Hypoventilation Syndrome
hypoventilation syndrome in very obese persons with excessive adipose tissue around the abdomen and diaphragm. it is characterized by diminished to absent ventilatory chemoresponsiveness; chronic hypoxia; hypercapnia; polycythemia; and long periods of sleep during day and night (hypersomnolence). it is a condition often related to obstructive sleep apnea but can occur separately.Obesity Management
an integrated professional approach to screening, evaluation, control, and reduction of abnormal weight gain.Obesity Paradox
an observation that high body mass index is sometimes associated with lower cardiovascular disease mortality in certain population, e.g., elderly.Obesity, Abdominal
a condition of having excess fat in the abdomen. abdominal obesity is typically defined as waist circumferences of 40 inches or more in men and 35 inches or more in women. abdominal obesity raises the risk of developing disorders, such as diabetes; hypertension; and metabolic syndrome.Obesity, Metabolically Benign
a sub-phenotype of obese individuals who have a risk for cardiovascular diseases between that of healthy individuals with normal weight and unhealthy individuals with obesity.Obesity, Morbid
the condition of weighing two, three, or more times the ideal weight, so called because it is associated with many serious and life-threatening disorders. in the body mass index, morbid obesity is defined as having a bmi greater than 40.0 kg/m2.Pediatric Obesity
body mass index in children (ages 2-12) and in adolescents (ages 13-18) that is grossly above the recommended cut-off for a specific age and sex. for infants less than 2 years of age, obesity is determined based on standard weight-for-length percentile measures.Pregnancy in Obesity
body mass index in pregnant people that is excessively above the recommended cut-off.Weight Prejudice
negative attitudes towards and beliefs about others because of their weight. these negative attitudes are manifested by stereotypes and/or prejudice towards people with weight over or under a cultural norm.Choroideremia
an x chromosome-linked abnormality characterized by atrophy of the choroid and degeneration of the retinal pigment epithelium causing night blindness.Weight Gain
increase in body weight over existing weight.Body Mass Index
an indicator of body density as determined by the relationship of body weight to body height. bmi=weight (kg)/height squared (m2). bmi correlates with body fat (adipose tissue). their relationship varies with age and gender. for adults, bmi falls into these categories: below 18.5 (underweight); 18.5-24.9 (normal); 25.0-29.9 (overweight); 30.0 and above (obese). (national center for health statistics, centers for disease control and prevention)
Patient EducationClinical
Obesity
Obesity is a disease that means having too much body fat. It is different from being overweight, which means weighing too much. Both terms mean that your weight is greater than what's considered healthy for your height.
The full article covers:
- What is obesity?
- What raises your risk of obesity?
- How is obesity diagnosed?
- What health problems can obesity cause?
- What are the treatments for obesity?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert E66.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About E66.9Overview
Is E66.9 (Overweight and obesity) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report obesity, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does E66.9 group to?
When obesity, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 640, 641, with relative weights from 0.7782 to 1.3356 depending on complications. Higher weights mean higher Medicare reimbursement.
Does E66.9 justify an inpatient admission?
Not on its own. The Medicare Code Editor lists this code as a questionable admission because obesity, unspecified is not usually sufficient justification for admission to an acute care hospital.
What is the ICD-9 equivalent of E66.9?
Under the General Equivalence Mappings, obesity, unspecified converts to ICD-9-CM 278.00 (obesity NOS). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:
- The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
- The condition places limitations on self-care, independent living, and social interactions.
