Billing codes · ICD-10-CM code
E66 obesity ICD-10 codes for nutrition claims
By Javier Alvarez · Updated · 5 min read
| Category | E66, Overweight and obesity |
|---|---|
| Billable codes | E66.01, E66.09, E66.1, E66.2, E66.3, E66.811, E66.812, E66.813, E66.89, E66.9 |
| Not billable (headers) | E66, E66.0, E66.8, E66.81 |
| Class codes | E66.811-E66.813, effective Oct 1, 2024 (FY2025) |
| Tabular note | Use additional code for BMI, if known (Z68.-) |
| Pregnancy | Code first O99.21- when obesity complicates pregnancy |
| Medicare MNT | Not a qualifying diagnosis on its own |
| FY2027 change | None to E66 (Oct 1, 2026) |
Weight management is a big share of RD private practice, and the obesity codes changed more in the last two years than in the decade before. If your claim templates predate October 2024, some of your E66 codes may be too vague, and at least one (E66.8) no longer exists as a billable code.
Which obesity code when
| Code | Descriptor | Use it when the provider documents… |
|---|---|---|
| E66.811 | Obesity, class 1 | Class 1 obesity |
| E66.812 | Obesity, class 2 | Class 2 obesity |
| E66.813 | Obesity, class 3 | Class 3 obesity (preferred over E66.01 when both are documented) |
| E66.01 | Morbid (severe) obesity due to excess calories | Morbid or severe obesity attributed to excess calories |
| E66.09 | Other obesity due to excess calories | Obesity due to excess calories, not morbid |
| E66.1 | Drug-induced obesity | Obesity caused by a medication (add the drug's adverse-effect code, per the tabular) |
| E66.2 | Morbid (severe) obesity with alveolar hypoventilation | Obesity hypoventilation syndrome |
| E66.3 | Overweight | Overweight, not obesity |
| E66.89 | Other obesity not elsewhere classified | A specified obesity type with no better code |
| E66.9 | Obesity, unspecified | "Obesity" with no class or type |
Related codes outside E66: E88.82 (obesity due to disruption of the MC4R pathway) and O99.21- (obesity complicating pregnancy, childbirth and the puerperium).
Headers you can't bill: E66, E66.0, E66.8 and E66.81. If a claim is rejected for an invalid diagnosis, check for one of these first.
The class codes added October 2024 (E66.811-E66.813)
The FY2025 update, effective October 1, 2024, added the obesity class subcategory, E66.81. It also made E66.8 a header and added E66.89 for "other obesity." The CDC's partner materials describe the classes by BMI: class 1 is generally 30 to <35, class 2 is 35 to <40, and class 3 is 40 or higher.
Section I.C.4.b of the Official Guidelines adds three rules:
- The provider documents the class. You can't assign E66.812 just because the BMI you measured is 37. The class must be documented by the provider in the medical record.
- Class codes can be combined with other obesity codes from Chapters 4 and 15 to fully describe the condition. For example, E66.1 (drug-induced) and a class code.
- Class 3 beats morbid obesity. If both class 3 and morbid obesity are documented, code only E66.813, because it's more specific.
No E66 codes changed in FY2027 (October 1, 2026).
Overweight (E66.3) vs. obesity
E66.3 is overweight. On nutrition claims it usually appears with Z68.25-Z68.29. Coverage for overweight alone is narrower than for obesity. Aetna's CPB 0049 covers nutritional counseling for overweight adults (BMI over 25) only when there are other cardiovascular risk factors: hypertension, dyslipidemia, impaired fasting glucose or metabolic syndrome. UnitedHealthcare's preventive policy lists E66.3 and Z68.25-Z68.29 in its cardiovascular-risk counseling row, not in the obesity row. For Aetna's full diagnosis list on one page, see the free Aetna billing cheat sheet.
So an overweight patient's claim often needs the risk factor too: E78.x, I10, R73.01 or E88.81x, as documented by the provider.
Pair every E66 code with a Z68 BMI code
The E66 category says to use an additional code for BMI, if known. Order matters:
| Position | Example | Rule |
|---|---|---|
| First | E66.812 | The provider's diagnosis leads |
| Next | Z68.37 | The BMI you measured; never first, never alone |
| Optional | Z71.3 | The counseling encounter, if the payer's policy uses it |
Your measured BMI can support the Z68 code (the guidelines name the dietitian as a typical source), but the E66 diagnosis must come from the provider. Full table and the FY2027 change to Z68.1: Z68 BMI codes.
Preventive vs. medical routing for weight counseling
Obesity counseling can pay under either benefit, depending on the plan's code lists:
- Preventive. The USPSTF gives a B grade to offering or referring adults with a BMI of 30 or higher to intensive, multicomponent behavioral interventions (2018). It gives a B to children 6 and older with high BMI (2024). UnitedHealthcare's MP.016.59 lists 97802-97804 under both, with obesity codes E66.01, E66.09, E66.1, E66.2, E66.811-E66.813, E66.89, E66.9 and E88.82, plus Z68.30-Z68.45 for adults or Z68.54-Z68.56 for children. Aetna's CPB 0049 treats counseling for obesity as a preventive service.
- Medical. When obesity is treated alongside a disease (type 2 diabetes, hypertension, fatty liver), or the plan has no preventive nutrition benefit, the claim may process under the medical benefit, with deductible and copay.
The same claim can route differently on two plans from the same carrier. Explain this to patients before the first visit. Preventive vs. medical benefits covers how.
Coverage caveats: weight-management exclusions
Some employer plans exclude "weight loss programs" or "obesity treatment" entirely, even when the carrier's standard policy covers them. Self-funded plans can write their own rules. Before the first visit, ask:
- Does the plan cover 97802/97803 with an obesity diagnosis?
- Is it preventive (no cost-share) or medical?
- Is there a visit limit, and is it shared with other providers?
- Is there a weight-management exclusion?
The verification call script has the wording. If the patient is on a GLP-1, GLP-1 nutrition billing covers how those visits usually bill.
What the note must show
- The provider's obesity diagnosis, with class if documented, traceable to the referral or chart.
- Height, weight and BMI for the visit.
- The nutrition assessment and intervention tied to weight, and time face to face for the units.
- For children: BMI-for-age percentile and the growth chart used.
Denials and fixes
| Symptom | Likely cause | Fix |
|---|---|---|
| Rejected: invalid diagnosis | E66.8 or a header billed | E66.811-E66.813 or E66.89 |
| CO-11 / CO-16 | Service line points only at Z68, or Z68 is first | Point to the E66 code; E66 first |
| CO-167 / PR-204 | Weight management excluded by the plan | Verify exclusions; patient discussion before billing |
| Paid to deductible | Plan's preventive list needs a different code set | Check the payer's preventive policy for its obesity row |
More in why nutrition claims get denied.
For the other diagnosis codes on nutrition claims, see the ICD-10 codes for dietitians reference.