overnutrition obesity disorder Obesity is a complex disease that may involve multiple environmental and genetic causes. See the subclass monogenic disease for genetic subtypes A disorder involving an excessive amount of body fat. HP:0001513 MEDGEN:18127 SCTID:414916001 UMLS:C0028754 ICD9:278.0 ICD9:278.00 DOID:9970 obesity EFO:0001073 obesity disease NCIT:C3283 Orphanet:521399