A relevant source might be [Nedarim 50b][1]:

> ההיא דאתיא לקמיה דרב יהודה מנהרדעא לדינא ואיתחייבת מן דינא אמרה ליה שמואל רבך הכי דנן אמר לה ידעת ליה אמרה ליה אין גוצא ורבה כריסיה אוכם ורבה שיניה אמר לה לבזוייה קאתית תיהוי ההיא אתתא בשמתא פקעה ומתה:

> A certain woman came before Rav Yehuda of the city of Neharde’a for judgment, and she was found guilty in the judgment of her case. She said to him: Would Shmuel your teacher have judged me in this manner? He said to her: Did you know him? She said to him: Yes. He was short and potbellied. He was dark and his teeth were large. He said to her: Did you come here to disparage him by describing him in this manner? Let that woman be in a state of excommunication. After he excommunicated her, her belly split open and she died, as a punishment for having disparaged a Torah scholar. 

[Maharik (teshuvah 185)][2] notes that even though on the surface she could have claimed that she didn't mean to be insulting, that wouldn't wash:

> וגדול' מזו מצינו בפ' הנודר מן המבושל (נדרים דף נ) גבי ההיא איתתא דאיחייבא בבי דינא דרב יודא כו' דא"ל ידעתי ליה אמרה ליה אין זוטר ורב כרסייה וכו' וא"ל לבזויי קא מכוונת אמר לה תהוי ההיא אתתא בשמתא וכו' ומביה ראיה במרדכי בת"ש השייכות לסדר נשים דמשמתינן אע"ג דמצי למימר לא לבזויי נתכוונתי כו'.

> Moreover, we find [the story from the Gemara cited above]. From this the Mordechai, in the teshuvos relevant to Seder Nashim, proves that we excommunicate someone [who talks this way], even though they could argue that they didn't mean to be insulting.

Granted, then, that in that case there's the additional factor of disparaging a talmid chacham, it does suggest that such a description is lashon hara.


  [1]: https://www.sefaria.org/Nedarim.50b.5?lang=bi&with=all&lang2=he
  [2]: https://www.sefaria.org/Teshuvot_Maharik.185.1?lang=he