During Katrina, we lost everything but water for seven days...the fresh running water was a life saver.
During Ike we lost power for three weeks, but we made it through without much problems.
The commercial areas (grocery stores)were up and running on the third day after Ike came through so there was little problem with food. The amount of food brought in was stunning. The grocery industry has disaster plans that are astonishing.
It worked out well but in Houston have had a lot of practice with this type of event.