وَإِنْ قَلَّتْ وَخَفِيَتْ سُمِّيَتْ رَمْزًا
If the intermediary links are few but subtle, the mode is called ramz.
«هُوَ سَمِينٌ رَخْوٌ» describes someone as fat and flabby, but in its rhetorical use it may hint at dullness or mental sluggishness. There is no long series of steps, yet the shift from bodily description to intended character is not transparent; hence it illustrates ramz.
This is a historical rhetorical association, not a sound general rule about a person’s intelligence from their body shape.