'bariatrician' originates from Modern English, ultimately from Greek elements: 'bari-' from Greek 'baros' meaning 'weight' and '-iatr-' from Greek 'iatros' meaning 'physician' or 'healer', with the English agent suffix '-ian' added.

'bariatrician' changed from the adjective and noun base 'bariatric' (formed from Greek roots 'bari-' + 'iatr-') and the formation of agent nouns in English, and eventually became the modern English noun 'bariatrician' in the 20th century.

Initially related to 'bariatrics' as the medical field concerned with weight, the term evolved to refer specifically to a physician who treats obesity and related conditions.