For me this would be impossible, but that is based on my definition of a BOB. For me a BOB is something that is supposed to be ready to go at a moments notice & that would provide water & high calorie food for me & my family on the run.

If I was to take it camping with me and eat some of the the peanut butter (now that it is open it will go stale faster), eat some of the food bars, drink the water, use some bandaids, cut up some of the rope, etc. - then I have just reduced the supplies in my BOB.

Now if your definition of a BOB only includes tools (FAK, gun/ammo, knife, rope, snare wire, etc.) then I guess you could make it serve as all three.

If your BOB does include food/water then you will always (and immediately) need to replace whatever is used. But it will take discipline that I must say I don't have. That is why I keep my BOB set aside at home. My BOB weighs 45 lbs so there is no way I would want to carry it everywhere with me, but that is just me.

The pack I carry back & forth to work everday (and take hiking/camping) is a reduced down form of a BOB, but I would want both if truly buggin' out.