I'd say first house and planets that you have there, if any. But I've also noticed that other aspects tend to add up to the first house, making some physical characteristics more prominent. For example, I've got Jupiter in the first house, and boy, do I tend to expand! But I also have Venus in Taurus that, with it's taste for good food and vine also points to weight issues. To put some more icing on the cake, my sixth house Neptune is in hard aspect to Moon, which makes me even more self-indulgent. So, I guess that more than one acpect and planetary position reveals our appearance.