Done 24 hour dry fast a couple of times. Depending on your purpose, stressing your body in this way probably does more harm than good. That goes for fasting in general, I think. That said, I didn't find it too difficult, just a little boring. Oxidation of fat does release water, so you won't die of thirst. Remember that skin is an organ, so if you're serious no long baths or showers, or swimming.