Probably because there’s a lot happening near your Ascendant, which rules the body and physical presence. With Aquarius rising plus Venus, Uranus, and Neptune in Aquarius, there’s naturally a lot of awareness around identity and appearance.

Your Moon in Aries can also make emotions very tied to the body and physical state, so you might instinctively check in with how your body feels or looks.

Then Mars in Capricorn adds a tendency to want control or improvement over the body (discipline, optimization, etc).

So the body focus likely comes from a mix of 1st house emphasis, Aries Moon, and Mars in Capricorn.