וַתֹּאכַ֙לְנָה֙ הַפָּר֔וֹת הָרַקּ֖וֹת וְהָרָע֑וֹת אֵ֣ת שֶׁ֧בַע הַפָּר֛וֹת הָרִאשֹׁנ֖וֹת הַבְּרִיאֹֽת׃
E as vacas magras e feias comiam as primeiras sete vacas gordas;
Radak on Genesis
הרקות , the ones mentioned as possessing only a thin layer of flesh as in verse 19.