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

E66.01 – Morbid (severe) obesity due to excess calories | ICD-10-CM

By Joshua Napilay on Jul 16, 2025.

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

The E66.01 is an ICD code that’s included in the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM), and it is used to designate “Morbid (severe) obesity due to excess calories.”

This ICD-10 code is meant to diagnose patients who are confirmed to be morbidly obese, and their obesity is the result of having excess calories. This means that the patient is morbidly obese because of overeating. By eating more than they need to, in a meal or a day, they leave excess calories in their body, which the body stores as body fat. The more excess calories are stored, the more body fat is produced. In the case of this ICD-10 code, excess calories have been stored that the patient has become morbidly obese.

Is the E66.01 billable?

Yes, the E66.01 ICD-10 code is billable and can be used to designate a patient for reimbursement purposes.

E66.01 clinical information:

Obesity refers to the condition where an individual has an excessive amount of body fat. Often, people mistakenly equate obesity with being overweight, which is understandable since obese individuals are indeed overweight. However, being overweight is not solely attributable to obesity, as other factors like muscle mass, bone density, and overall body water content also play a role in determining weight.

Obesity poses significant risks to a person's health, potentially leading to severe complications, including life-threatening conditions like diabetes, cancer, arthritis, and heart disease.

To address obesity, individuals should consider lifestyle changes, particularly regarding their dietary habits and exercise routine. Adopting a low-calorie diet and regular physical activity can also gradually reduce weight and body fat.

E66.01 synonyms include:

Morbid obesity
Obese class III
Severe obesity

Other ICD-10 codes commonly used for obesity:

E66 - Overweight and obesity
E66.0 - Obesity due to excess calories
E66.09 - Other obesity due to excess calories
E66.1 - Drug-induced obesity
E66.2 - Morbid (severe) obesity with alveolar hypoventilation
E66.3 - Overweight
E66.8 - Other obesity
E66.9 - Obesity, unspecified

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