As a cat owner for many years, I have no qualms about heading off for a week-end and leaving my cats outside. I don't leave out food for them because this only attracts vermin - mice, rats, grey squirrels, jack-daws, crows, pigeons, etc.
All the more reason to leave out food when you're gone, the cats will have a great time with food plus vermin! They'll wish you went every week.