ICD-10 Code E66.01 – Morbid (severe) obesity due to excess calories (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code E66.01 – Morbid (severe) obesity due to excess calories
What it is
E66.01 identifies morbid, or severe, obesity caused by excess calorie intake. Use it when the record clearly links the obesity to overeating or high caloric intake.
Clinical signs
Clinical features vary; refer to documentation. Commonly, the chart describes severe obesity with a documented cause of excess calories, and may note related functional limits or obesity-associated conditions.
When to use this code
Use E66.01 when the provider documents morbid or severe obesity and specifies excess calories as the cause. You should code it from the assessment, problem list, or discharge summary when that linkage is explicit.
If the chart only says obesity, or does not state the cause, check documentation before assigning this code. Pair it with additional obesity-related codes when the record supports them.
Do not use for
Do not use this code for obesity without a stated cause, or when the record describes overweight only. Do not assume excess calories if the documentation does not say so.
Coding tip
Code the documented cause exactly; if “excess calories” is not stated, query or choose the more specific supported obesity code.