I could go about half a day I suppose. At least on purpose. I would miss my coffee and the comfort of a hot meal. Heck, I even carry a small pint thermos when I go fishing for the day and carry a small pack with food and cooking gear while taking day hikes on BP trips. When I was young,I could put up with a lot more discomfort than I'm willing to now. Good for you though and lots of luck and if we meet sometime on the trail, I'll make you a "hot meal".