I don't think you can actually assign a code based on the provider's documentation since there isn't an ICD-10 code that corresponds to the class of obesity. I did find this little tidbit from the CDC's website in an article titled
Defining Adult Overweight & Obesity.
View attachment 6655
Does your provider document the BMI anywhere in the chart and do you need the BMI for your claim to be processed by the payer? If the BMI is not documented and you need it for your claim you probably need to query the provider. If the patient has an MA plan it is likely important that the BMI be included because of Risk Adjustment scoring, which may impact your provider's reimbursement from the MA plan as the MA plan needs it for reimbursement from CMS for covering the MA patient.